Accio! (Goblet of Fire, page 68)
Etymology: L. accedo (to approach, come near / (things) to be added).
The Summoning Charm (incantation: "Accio!") is used to bring an object to you, wherever it may be. Concentrating is essential to succeeding in the spell; the further away an object is and the larger it is, the harder it is to summon. The two most difficult Summoning Charms are in Goblet of Fire and Order of the Phoenix. In Goblet of Fire, Harry summons his Firebolt from inside the castle to the grounds to use it for the first task of the Triwizard Tournament. In Order of the Phoenix, the potency of the charm is demonstrated when Fred and George Weasley summon their brooms (which were chained to a wall) from another part of the castle.

Age Line Charm (Goblet of Fire, page 256)
The incantation for the age line charm is unknown, but the effect is a thin golden line drawn on the surface of the floor that prevents anyone who is too young (or possibly the reverse, too old) from crossing. The effect, in Fred and George’s case, was being transformed into much older versions of themselves.

Aguamenti! (Half-Blood Prince, page 574)
Etymology: L. Agua (water) + Mentis (Mind).
"Aguamenti!", which is taught in the sixth year, is a spell whose affect is a clear jet or fountain of water being emitted from the castor’s wand.

Air-dry Charm (Half-Blood Prince, page 558)
The charm blows a rush of warm air from the castor’s wand. Dumbledore uses the charm to dry off himself and Harry when they travel to the cave.

Alohomora! (Sorcerer's Stone, page 160)
Etymology: Hawaiian. Aloha (goodbye) L. + mora (delay)
The Alohomora Charm (incantation: "Alohomora!") is used to unlock doors or other objects that are locked. The charm also unlocks magically locked doors or objects (see "Colloportus!"). Though the charm comes in handy for Harry, Hermione, and Ron throughout the books, it is not powerful. As shown in Chapter 34, "The Department of Mysteries," in Order of the Phoenix, The Alohomora Charm does not unlock all magically locked doors or objects.

Anapneo! (Half-Blood Prince, page 144)
Etymology: Greek. Anapneo (Breathe).
A useful spell that clears the blocked airway of the castor’s target. Slughorn uses the spell to save a student's life.

Anti-Apparition Spell:
The anti-apparition spell prevents a witch or wizard from apparating. The spell is cast over the grounds of Hogwarts though it was lifted in the great hall during Harry’s sixth year to allow the students to practice for apparition tests.

Anti-Cheating Spell (Sorcerer's Stone, page 262)
The spell is cast on student’s quills before taking tests which presumably stops a student from cheating.

Anti-Disapparition Spell: (Order of the Phoenix page 817)
The anti-disapparition spell prevents a witch or wizard from disapparating; Dumbledore uses it on the recently captured Death Eaters in the Ministry.

Antler jinx (Order of the Phoenix page 677)
The jinx causes antlers to sprout from the victim’s head. In Order of the Phoenix, Pansy Parkinson is hit with this jinx which forces her to miss class for a day.

Aparecium! (Chamber of Secrets, page 233)
Etymology: L. appareo (to become visible, appear, manifest).
"Aparecium!" is used only once by Hermione in an attempt to reveal the hidden contents of Tom Riddle's diary. Though the spell is unsuccessful, Hermione says that it is used to reveal invisible ink.

Apparition/ Disapparition:
An advanced non-verbal spell that allows a witch or wizard to disappear from one place and instantaneously appear at another. Apparating is marked by a loud cracking noise and a sensation similar to being forced through a very tight rubber tube. Apparition can also be performed with multiple passengers via the apparator touching the person they wish to bring with them.

Arrow-wand Charm (Quidditch through the Ages, Ch. 7)
The charm causes arrows to shoot from the castor’s wand. The charm was popular with Appleby Arrows supporters who would use it to celebrate goals; it was outlawed in 1894.

Avada Kedavra! (Goblet of Fire, page 215)
Etymology: Aramaic. abracadabra (ancient spell meaning "let the thing be destroyed")
The Killing Curse (incantation: "Avada Kedavra!") is considered by most wizards the worst curse, as it kills whoever or whatever it is cast upon. The curse is one of three Unforgivable Curses - curses that are illegal and can land a wizard in Azkaban Prison for using them (see "Imperio!" and "Crucio!").

Avis! (Goblet of Fire, page 309)
Etymology: L. Avis (bird)
"Avis!" is used when examining a wand; it will cause small, twittering birds to fly out of the end of a wand in working condition.

Babbling Curse (Chamber of Secret, page 161)
The exact effect is never mentioned in canon but we can assume it causes the castor’s victim to babble for an extended period of time. Lockhart claims to have cured a “simple Transylvanian villager” of the curse.

Banishing Charm (Goblet of Fire, page 479)
The opposite of the Summoning charm, the incantation causes an object to fly away from the castor; it is then ‘banished’.

Bat-Boogey Hex (Half Blood Prince, Ch. 7)
This nasty hex causes the victim’s boogies to grow to the size of bats and then sprout wings and attack the victim’s face. Ginny is said to be especially gifted at this particular hex.

Bewitched Sleep (Goblet of Fire, page 509)
The charm causes the target to be placed in a deep artificial sleep in which (s)he doesn't need to breathe. Dumbledore places Ron, Hermione, Gabrielle Delacour and Cho in this sleep-like state when they are placed in the care of the mere people during the second triwizard task.

Boil-Covering spell (Chamber of Secrets, page 185)
The boil-covering spell causes the target to become covered with boils. Fred and George, for some reason, use it to try to cheer up Ginny.

Bubble-Head Charm (Goblet of Fire, page 506)
The bubble-head charm surrounds a person’s head in a large air-bubble. Both Cedric and Fleur use this charm in the second task of the Triwizard Tournament. It was also very popular towards the end of Harry’s fifth year as students used the charm in effort to combat the growing number of dungbombs and stinkpellets being set off.

Cheering Charm (Prisoner of Azkaban, page 294)
The cheering charm is a third-year charm which cheers a person up.

Colloportus! (Order of the Phoenix, page 788)
Etymology: L. colligo (to bind, tie, fasten together)
"Colloportus!" is used to lock doors or objects that can be locked. However, the spell is not of much use unless dealing with Muggles or a wandless wizard or witch, because the Alohomora Charm will unlock anything locked by "Colloportus!"

Confundus Charm (Prisoner of Azkaban, page 386)
Etymology: L. Confundo (to perplex).
The confundus charm causes the person or object it is cast upon to become confused or misguided.

Conjunctivitis Curse (Goblet of Fire, page 406)
Etymology: L. Conjunctiva (relating to the eye) + itis (inflammation)
The curse affects the visibility of the victim making it very difficult to see and possibly causing pain or irritation in the eyes. Sirius tries to suggest Harry use this spell on the dragon in the first task; Krum does use it.

Conjuring Charm:
Conjures items out of thin air for the castor. Used multiple times through the books for everything from chairs, to liquid, to even sleeping bags.

Corn-Flaked skin Jinx (Order of the Phoenix p. 677)
Warrington, of the Slytherin Quidditch team, is hit with this jinx which makes his skin look as though he had been coated in cornflakes.

Crucio! (Goblet of Fire, page 214)
Etymology: L. crucio (to torture, torment)
The Cruciatus Curse (incantation: "Crucio!") inflicts severe pain on whoever it is cast on. It is used mainly by Voldemort and his Death Eaters when torturing someone. Rowling describes the pain as this: "White-hot knives were piercing every inch of his skin, his head was surely going to burst with pain, he was screaming more loudly than he'd ever screamed in his life..." The length of time the curse is in effect is unknown, but it is presumed to stop after 15 seconds - 1 minute. Wizards and witches (i.e. Frank and Alice Longbottom) can be tortured to the point of insanity by the curse. This explains why the Cruciatus Curse is one of three Unforgivable Curses - curses that are illegal and can land a wizard in Azkaban Prison for using them (see "Avada Kedavra"! and "Imperio!").

Cushioning Charm (Quidditch Through the Ages, Ch. 9)
The cushioning charm creates an invisible cushion on the handle of a broom making it much more comfortable to fly for extended periods of time.

Deletrius! (Goblet of Fire, page 136)
Etymology: L. deleo (to destroy, wipe out, erase)
"Deletrius!" is used only once throughout the Harry Potter series in order to vanish the "echo" of a spell conjured by Prior Incantato! The incantation comes from the Latin word deleo, which means "to destroy, wipe out, erase." This leads to the assumption that the spell would also delete objects, although this has not been proven by the books.

Densaugeo! (Goblet of Fire, page 309)
Etymology: L. dens (tooth), + auctus (growth, enlargement, increase)
"Densaugeo!" causes a person's teeth to grow rapidly. At what point the spell stops is unknown; when Draco hit Hermione with the spell in Goblet of Fire, Hermione's teeth grew down past her collar. The spell can be undone by shrinking the affected teeth.

Diffindo! (Goblet of Fire, page 340)
Etymology: L. diffundo (to spread, pour forth, scatter)
"Diffindo!" causes an object to split or break. Wand aim is essential to the success of this spell. It has only been used once in the Harry Potter books (see above reference).

Disapparition/ Aapparition:
Etymology: L. Appareo (To appear)
An advanced non-verbal spell that allows a witch or wizard to disappear from one place and instantaneously appear at another. Apparating is marked by a loud cracking noise and a sensation similar to being forced through a very tight rubber tube. Apparition can also be performed with multiple passengers via the apparator touching the person they wish to bring with them.

Disillusionment Charm (Order of the Phoenix, page 54)
The disillusionment charm is a concealment charm that feels something like a flood of cold running down one’s body. It hides the magical nature of a person, place, or thing. Hippogriffs and Winged horses are allowed to be kept by wizards so long as they have this charm placed upon them so muggles’ attention isn’t drawn to them.

Dissendium! (Prisoner of Azkaban, page 195)
Etymology: L. dissimulo - antonym (to conceal, disguise, keep secret)
The incantation "Dissendium!" combined with a tap of the wand will open up the hump of a statue of a humpbacked, one-eyed witch (located on the third-floor corridor of Hogwarts). Going through the opened statue leads to a secret path to the wizard village Hogsmeade.

Drought Charm (Goblet of Fire, page 486)
Dries up relatively small amounts of water such as puddles and ponds.

Engorgio! (Goblet of Fire, page 214)
Etymology: Unknown
"Engorgio!" causes something to become several times its normal mass. Moody uses the spell on a spider during the unforgivable curse lesson.

Ennervate! (Goblet of Fire, page 133)
Latin Root: Unknown
"Ennervate!" is used to revive persons who have either been knocked unconscious by normal means or by the Stunning Spell, "Stupefy!" When someone is revived by this spell, their eyes suddenly open and they are dazed. They quickly come to their senses and regain composure.

Entrail-Expelling Curse (Order of the Phoenix, page 487)
A very disturbing spell that presumably causes one’s entrails (intestines) to expel from his or her rear. It was invented by Urquhart Rackharrow

Episkey! (Half-Blood Prince, page 157)
Etymology: Greek. Episkeyazo (To repair)
"Episkey!" Heals minor damage that has been done to a body part.

Evanesco! (Order of the Phoenix, page 234)
Etymology: L. evanescence (to vanish, to disappear, empty)
"Evanesco!" causes what it is cast upon to disappear. In Order of the Phoenix, the spell is used on scrolls and potions. Whether or not the disappearing object vanishes completely is unknown; a spell to bring the object back may exist, but is not verifiable.

Expecto Patronum! (Prisoner of Azkaban, page 238)
Etymology: L. exspecto (to wait for, look for, expect), + patronus (patron, protector)
The Patronus Charm (incantation: "Expecto Patronum!") is highly advanced magic, well beyond the Ordinary Wizarding Level, used to ward off dementors. When used properly, the spell creates a Patronus, which is a guardian that acts as a shield between the caster and the dementor. Each Patronus is unique to the wizard or witch who conjures it, and reflects their personality. In order for the spell to work properly, the incantation must be spoken while the caster concentrates on a extraordinarily happy memory. This causes a Patronus to be conjured; it is successful in warding off dementors because it is "a projection of the very things that the dementor feeds upon - hope, happiness, the desire to survive - but it cannot feel despair, as real humans can, so the dementors can't hurt it." (Prisoner of Azkaban, page 238)

Expelliarmus! (Chamber of Secrets, page 190)
Etymology: L. expello (to drive out, expel, force out, banish)
The Disarming Charm (incantation: "Expelliarmus!") is used to disarm someone, and is most commonly used while dueling. Though a simple spell, it can be used to get wizards and witches out of tight situations and close encounters - it saved Harry Potter's life in Goblet of Fire.

Extinguishing Spell (Goblet of Fire, p. 328
Naturally, the extinguishing spell extinguishes fires.

Fidelius Charm (Prisoner of Azkaban, page 205)
Etymology: L. Fidelis (Faithful)
“An immensely complex spell involving the magical concealment of a secret inside a single, living soul. The information is hidden inside the chosen person, or Secret-Keeper, and is henceforth impossible to find -- unless, of course, the Secret-Keeper chooses to divulge it.” If the secret-keeper dies, the secret dies with him or her.

Ferula! (Prisoner of Azkaban, page 376)
Etymology: Unknown
"Ferula!" creates a splint of bandages, a temporary fix for an injured or broken limb.

Finite Incantatem! (Chamber of Secrets, page 192)
Etymology: L. finis (end, limit)
"Finite Incantatem!" is used by Professor Gilderoy Lockhart in Chamber of Secrets, and it stops the effects of both Harry Potter and Draco Malfoy's spells. The spell also works without the "Incantatem" portion of the incantation, which was proved by Remus Lupin in Order of the Phoenix.

Flagrate! (Order of the Phoenix, page 772)
Etymology: L. flagro (to blaze, glow, flame)
"Flagrate!" was used in Order of the Phoenix to mark doors in the Department of Mysteries with a fiery "X". This allowed Harry, Hermione, Ron, Neville, Ginny, and Luna to know which doors they had already gone through.

Flame-Freezing Charm (Prisoner of Azkaban, page 2)
The charm changes the properties of fire so that the flames produce only a gentle tickling sensation.

Fur-growing Spell (Chamber of Secrets, page 185)
The spell causes the target to grow fur.

Furnunculus! (Goblet of Fire, page 298)
Etymology: L. furunculus (boil)
The Furnunculus Curse (incantation: "Furnunculus!") causes ugly boils to break out all over whoever the curse is cast upon. The Furnunculus Curse should not be mixed with Jelly-Legs; tentacles will sprout all over the victim's face.

Golden Bubble Charm (Sorcerer’s Stone, page 197)
The actual name of the charm is unknown, but this refers to the charm which causes non-popping golden bubbles to blossom out of the castor’s wand. Flitwick uses the charm for the Christmas decorations in the Great Hall.

Homorphus Charm (Chamber of Secrets, page 162)
Etymology: Greek. Homo (Same) or L. Homo (Man) + English. Morph. (Change)
Though its exact effects are unknown, Lockhart claims he used it to defeat a werewolf. Perhaps it is used to turn a werewolf into a man, or to turn oneself into the shape of a werewolf thus fooling it.

Horned Tongue Hex (Goblet of Fire, page 339)
Presumably transforms the victim’s tongue into a horn. Harry considers using it on the Hungarian Horntail but decides against it.

Hurling Hex (Prisoner of Azkaban, Ch. 12
A hex placed on a broom that presumably causes the broom to hurl the rider off. Flitwick checks Harry’s Firebolt for this hex when inspecting it in Prisoner of Azkaban.

Impedimenta! (Goblet of Fire, page 626)
Etymology: L. impedimentum (hindrance, impediment, obstacle, difficulty)
"Impedimenta!" slows down an attacker. If the spell is cast upon armor or other metal objects, it will backfire. If the spell is cast upon someone who is standing still, the person standing still will either freeze and be unable to move until they are "unfrozen" or will be knocked off of their feet.

Imperturbable Charm (Order of the Phoenix, page 69)
Etymology: L. Imperturbatus (Calm).
The imperturbable charm creates a magical seal on an object, such as a door, making it impossible for anyone to eavesdrop on what is going on on the other side.

Inanimatus Conjurus (Order of the Phoenix, page 295)
Etymology: L. Inanimus (not living) + Coniurus (conjure).
Though its affect is never given, it presumably has something to do with conjuring inanimate objects.

Imperio! (Goblet of Fire, page 214)
Etymology: L. imperium (power to command, authority, command, rule, control)
The Imperius Curse (incantation: "Imperio!") is used to control the actions of a person. Although few have the willpower to resist the curse, many wizards and witches cannot. Because wizards can completely control the actions of others when they are under this curse, it is one of the three Unforgivable Curses - curses that are illegal and can land a wizard in Azkaban Prison for using them (see "Avada Kedavra!" and "Crucio!").

Impervius! (Prisoner of Azkaban, page 177)
Etymology: L. in (not) + pervius (letting things through)
"Impervius!" was used by Hermione Granger on Harry Potter's glasses in the above reference, and it caused them to repel water. The spell was also used on the faces of the players on the Gryffindor Quidditch team in Order of the Phoenix, giving the players better visibility during practice.

Incarcerous! (Order of the Phoenix, page 755)
Etymology: L. carcer (prison, cell, jail, dungeon)
"Incarcerous!" has been used only once in the Harry Potter books, by Professor Umbridge (see above reference). When Umbridge cast the spell on Magorian the centaur, "ropes flew out of midair like thick snakes, wrapping themselves tightly around the centaur's torso and trapping his arms."

Incendio! (Goblet of Fire, page 47)
Etymology: L. incendia (fire)
"Incendio!" causes a fire to start, and it most commonly used on a fireplace. We are led to the belief that the spell may not work on human beings, due to the fact that it is not an Unforgiveable Curse.

Jelly Legs Jinx (Goblet of Fire, page 608)
The jelly legs jinx causes the victim's legs to wobble uncontrollably like jelly.

Knitting Charm (Order of the Phoenix, page 350)
The knitting charm causes knitting needles to knit on their own.

Langlock! (Half-Blood Prince, page 238)
"Langlock!" Renders the victim speechless by gluing his/her tongue to the top of his/her mouth.

Legilimens! (Order of the Phoenix, page 534)
Etymology: L. lego (to gather, choose, collect, pass through, read) + mens (mind)
"Legilimens!" is mostly used by accomplished Legilimens, those who can read minds. The spell is used when attempting to break into someone else's mind and access their memories - usually memories that they fear.

Levicorpus! (Half-Blood Prince, page 238)
Etymology: L. Levo (To lift up) + Corpus (Body)
Invented by Severus Snape, this spell dangles the victim upside down in the air by his/her ankle.

Liberacorpus! (Half-Blood Prince, page 239)
Etymology: L. Liber (Free) + Corpus (Body)
The counter to Levicorpus, this curse, also invented by Snape, frees the target from the Levicorpus jinx.

Light as a Feather Charm (Prisoner of Azkaban, page 32)
This charm makes objects as light as a feather. Harry considers using the charm on his trunk when he runs away from the Dursley’s.

Locomotor! (Order of the Phoenix, page 53)
Etymology: L. locus (to place, put, position), + motio (to move)
"Locomotor!" causes the object(s) that it is cast upon to levitate. Both of the times the spell is used throughout the books, it was cast on a trunk. In order for the spell to work most efficiently, the name of the object should be stated after the word "Locomotor." Example: "Locomotor trunk!"

Locomotor Mortis! (Sorcerer’s Stone, page 217)
Etymology: Locus (to place, put, position) + Motio (to move) + Mortis (death/corpse)
Not to be confused with the Locomotor incantation, this spell locks the victim’s legs together rendering him/her immobile.

Lumos! (Chanber of Secrets, page 302)
Etymology: L. luma (light)
"Lumos!" is one of the most commonly used spells, because it is a simple spell and useful. As its Latin root implies, "Lumos!" causes a light to appear at the end of the wand that cast the spell. The incantation "Nox!" is spoken when the bearer of the wand wishes for the light to go out.

Mobili-! (Prisoner of Azkaban, page 201, 377)
Etymology: L. mobili (to move), corpus (body), arbustus (planted with trees)
"Mobili-!" allows the caster to move an object. It has only been used twice throughout the Harry Potter series (see above references), both times with different suffixes. The first usage was by Hermione to move a Christmas tree in the Three Broomsticks. The second was to move the body of Professor Snape, who was unconscious at the time. The spell most likely works on corpses and conscious bodies, but there is no evidence to support this. It is interesting to note that the suffix changes according to the object being moved.

Morsmordre! (Goblet of Fire, page 128)
Etymology: L. mors mortis (death)
"Morsmordre!" is the incantation used when a wizard creates the Dark Mark, the sign of Voldemort. The Dark Mark has long been feared, because it was cast over the houses of wizards and witches who had been slain by Voldemort or his Death Eaters.

Muffliato! (Half-Blood Prince, page 238)
Etymology: English. Muffle (to deaden or dampen)
"Muffliato!" fills the ears of those near the witch or wizard casting the spell with an undetectable light buzzing so that the castor can carry on a conversation without being overheard.

Nox! (Prisoner of Azkaban, page 338)
Etymology: L. nox (darkness)
"Nox!" is used to put out the light created by "Lumos!" The spell presumably does nothing to the caster's wand if "Lumos!" has not previously been cast. The use of the spell on lit objects which are disconnected from the caster's wand is unknown.

Obliteration Charm (Order of the Phoenix, page 440)
Etymology: L. Oblitesco (To conceal oneself)
Hermione uses the obliteration charm in Order of the Phoenix to conceal the tracks she, Harry, and Ron leave while they are sneaking to and from Hagrid’s Cabin.

Obliviate! (Chamber of Secrets, page 303)
Etymology: L. oblivio (forgetfulness, oblivion)
The Memory Charm (incantation: "Obliviate!") causes whoever it is cast upon to lose most of their memory. A variant of this spell may be used for memory modifications, but the spell itself is much more powerful than a mere modification. Though a spell may exist that can bring someone's memory back, it is not commonly known in the wizarding world. In Chamber of Secrets, Professor Lockhart lost most of his memory due to this spell. Though he retained the ability to speak and understand the English language, he could no longer recall many basic things (e.g. names, uses of objects, who he was).

Occlumency
Etymology: L.. Occlusum (to block or close) + Mens (mind)
Occlumency is a branch of magic specializing in the practice of blocking one’s mind from an outside mental attack.

Oppugno! (Half-Blood Prince, page 302)
Etymology: L. Oppugno (To attack)
The "Oppugno!" charm causes conjured creatures to attack a target specified by the castor.

Orchideous! (Goblet of Fire, page 308)
Etymology: L. Orchideae (Orchid family of Plants)
The charm conjures a bouquet of flowers that appear at the end of the castor’s wand. Mr Ollivander uses the spell to test Fleur’s wand during the weighing of the wands.

Permanent Sticking Charm (Order of the phoenix, page 110)
We’ve only really seen this spell's effects twice in the series, and both times it was on portraits: Sirius’ Mother’s portrait in the Black family house and the Portrait in the Muggle Prime Minister’s office. The permanent sticking charm makes if very difficult (if not impossible) to remove two things from each other once the charm has been performed.

Peskipiksi Pesternomi (Chamber of Secrets, page 102)
Etymology: Pesky – Pixie – Pester – No – Me = Pesky Pixie don’t pester me.
This funny spell may very well have been made up by Lockhart on the spot. It didn’t work but was meant to somehow subdue or immobilize the pixies Lockhart had let loose in his classroom.

Petrificus Totalus! (Sorcerer's Stone, page 273)
Etymology: L. petra (rock) + totus (whole)
The Full-Body Bind (incantation: "Petrificus Totalus!") causes whoever it is cast upon to lose mobility. Rowling describes the effects of the spell best: "Neville's arms snapped to his sides. His legs sprang together. His whole body rigid, he swayed where he stood and then fell flat on his face, stiff as a board....Neville's jaws were jammed together so he couldn't speak. Only his eyes were moving, looking at them in horror."

Point Me! (Goblet of Fire, page 622)
The Four-Point spell (incantation: "Point Me!") is used as a directional tool. When the caster places his or her wand in their open palm and utters the incantation, their wand will point north, allowing the caster to know what direction they are going.

Portus! (Order of the Phoenix, page 472)
Etymology: L. porta (gate, entrance)
"Portus!" is used to turn an object into a Portkey. Portkeys, first introduced in Goblet of Fire, are seemingly normal objects that transport those in direct physical contact with it to a certain place, usually at a prearranged time. Due to the dangers Portkeys present, authorization is required prior to using the spell. Some Portkeys can be made to transport those in direct physical contact to a certain place the moment they touch it rather than at a prearranged time. Presumably, any object can be turned into a Portkey.

Protean Charm (Order of the Phoenix, page 398)
Etymology: In Greek Mythology the sea-god Proteus possessed the ability to change form.
The protean charm changes the form of an object. Hermione places the charm on the coins the DA use to communicate which enables them to know when to meet.

Priori Incantatem! (Goblet of Fire, page 136)
Etymology: L. priori prius (former, prior)
The Reverse Spell effect (incantation: "Priori Incantatem!") causes a wand to regurgitate an echo of spells it has performed in reverse. When used in Goblet of Fire on a wand that had conjured the Dark Mark (see "Morsmorde!"), a shadow of the gigantic serpent-tongued skull was emitted from the wand.

Protego! (Order of the Phoenix, page 803)
Etymology: L. protego (to protect)
The Shield Charm (incantation: "Protego!") creates a sheild around the caster, protecting them from most harmful spells. Spells exist that can still cause damage to whoever it is cast upon even if The Shield Charm is in use, but the Charm usually saves someone from the worst of the spell cast upon them.

Quietus! (Goblet of Fire, page 116)
Etymology: L. quies quietis (quiet, rest, peace)
"Quietus!" is used to counter the effect of the spell "Sonorus!", which amplifies the voice of whoever it is cast upon. "Quietus!" merely makes the voice softer; it does not completely silence it. The spell "Silencio!" completely quiets one's voice.

Reducio! (Goblet of Fire, page 215)
Etymology: L. reduco (to lead back, bring back, return)
"Reducio!" causes solid objects it is cast upon to shrink. If "Engorgio!" has previously been cast on an object, "Reducio!" will cause it to reduce to its original size.

Reducto! (Order of the Phoenix, page 623)
Etymology: L. Reductus (to reduce)
The Reducto charm blasts away the target object.

Refilling charm
The refilling charm, obviously, refills a target container with a liquid determined by the castor.

Relashio! (Goblet of Fire, page 496)
Etymology: Unknown
"Relashio!" presumably shoots sparks at someone; however, the only usage of the spell in the books was underwater. The underwater effect varies - it instead pelts a jet of boiling water at someone.

Rennervate! (Goblet of Fire, page 133)
Etymology: L. Re (Again) + novare (new) = to make new again
Rennervate revives those who have been stunned, passed out, or otherwise knocked unconscious.

Reparo! (Goblet of Fire, page 169)
Etymology: L. reparo (to restore, renew)
"Reparo!" does exactly what its Latin root suggests - fixes things that are broken. Examples in the Harry Potter books include fixing broken glass, broken china, broken jars, and broken cups. "Reparo!" only works on solid objects.

Reverse Gravity Mist (Goblet of Fire, page 643)
Possibly created by a spell the “odd golden mist” reverses the effects of gravity so that up is down and down is up; Though you are on the ground you feel as though you are upside-down.

Rictusempra! (Chamber of Secrets, page 192)
Etymology: L. rideo risi risum (to laugh at, laugh) + simper (always)
The Tickling Charm (incantation: "Rictusempra!") causes whoever it is cast upon to start laughing uncontrollably. The effects of the charm can be stopped by the spell "Finite Incanatem!"  When the Tickling Charm is cast, a jet of silver light comes out of the caster's wand and hits the victim.

Riddikulus! (Prisoner of Azkaban, page 134)
Etymology: L. ridiculus (facetious, laughable)
The spell "Riddikulus!" is used to get rid of a boggart. In order for the spell to work properly, the caster must envision the boggart as something that it finds amusing prior to casting the spell. The spell only turns the boggart into something humorous - what actually gets rid of a boggart is laughter.

Room-securing Spell (Goblet of Fire, page 469)
The room-securing spell secures a room (no suprise there!) by preventing intruders from entering. Snape uses this spell on his office and we are told that only a powerful wizard would be able to break the spell to enter.

Scourgify! (Order of the Phoenix, page 53)
Etymology: Unknown
"Scourgify!" is used to clean. Examples from the fifth Harry Potter book include cleaning Hedwig the owl's cage and ridding a train compartment of a sticky substance called Stinksap. If cast on someone's mouth, the spell causes pink soap bubbles to stream from their mouth and froth to cover their lips, which chokes the victim.

Sectumsempra! (Half-Blood Prince, page 522)
Etymology: L. Sectus p.p. secare (to cut) + simper (always)
Invented by Snape, the Half-Blood Prince, this dark spell slashes the victim multiple times leaving deep bleeding lacerations. With immediate treatment there is only, at worst, a bit of scarring, at best, no blemishes or disfigurement. It doesn’t do much good on inferi, however.

Serpensortia! (Chamber of Secrets, page 194)
Etymology: L. serpere (to creep [snake]) + English. sort (type or kind)
"Serpensortia!" causes a long black snake, poised to attack, shoot out of the caster's wand. It has only been used once throughout the Harry Potter series (see above reference).

Silencio! (Order of the Phoenix, page 375)
Etymology: L. silens (silent, still)
The Silencing Charm (incantation: "Silencio!") causes whoever it is cast upon to lose the ability to make audible noises. A counter curse most likely exists ("Sonorus!" would probably work), but whoever was affected by the spell, wizard or not, would be unable to utter the incantation for the counter curse. The charm works best with a sharp jab of the wand.

Sonorus! (Goblet of Fire, page 102)
Etymology: L. sono (to make a noise, to sing)
"Sonorus!" amplifies your voice in a way similar to that of the muggle "microphone." The spell "Quietus!" will bring the caster's voice back to normal.

Specialis Revelio! (Half-Blood Prince, page 193)
Etymology: L. specialis, (kind) + revelatum (to unveil).
"Specialis Revelio!" identifies the ingredients or enchantments in a potion or on a target object.

Stupefy! (Goblet of Fire, page 129)
Etymology: L. stupefactus (stunned)
The Stunning Spell (incantation: "Stupefy!") stuns whoever it is cast upon, knocking them temporarily unconscious. The victim can be brought back to consciousness by the spell "Ennervate!"  A normal Stunning Spell will not cause any damage to whoever it is cast upon, but many Stunners cast at once can cause long-term damage.

Tarantallegra! (Chamber of Secrets, page 192)
Etymology: Italian. tarantella (a dance)
"Tarantallegra!" causes the legs of whoever it is cast upon to jerk around out of control, in a kind of quickstep. The spell is used in the second and fifth Harry Potter books and can be stopped by the spell "Finite Incantatem!"

Tergeo! (Half-Blood Prince, page 162)
Etymology: L. Tergeo (to wipe off)
"Tergeo!" wipes up a target substance. Hermione uses this spell to clean the blood off Harry’s face after Malfoy breaks his nose.

Toenail-growing Hex (Half-Blood Prince, page 238)
The hex causes the target’s toenails to grow at an increasing rate. It is one of the many spells invented by Snape, the Half-Blood Prince.

Tripping Jinx (Order of the Phoenix, page 609)
The jinx trips the target. Malfoy uses this jinx on Harry when running away from the Room of Requirement.

Unbreakable charm (Goblet of Fire, page 728)
The charm makes an object unbreakable. Hermione uses this charm on the jar in which she traps the bug, Rita Skeeter.

Waddiwasi! (Prisoner of Azkaban, page 131)
Etymology: Unknown
The exact effects of the spell are unclear, but the following happened the only time it was used in the Harry Potter books (see above reference): "With the force of a bullet, the wad of chewing gum shot out of the keyhole and straight down Peeves's left nostril." Professor Lupin cast the spell on the piece of chewing gum, which had been stuck in a keyhole by Peeves.

Wiggle and Twitchy ears Hex (Goblet of Fire, page 547)
Harry was hit by this hex in Defense Against the Dark Arts class; it causes the victim’s ears to wiggle and twitch.

Wingardium Leviosa! (Sorcerer's Stone, page 171)
Etymology: L. levo (to raise, lift up)
"Wingardium Leviosa!" causes an object to levitate. Once the caster has an object in the air, it can be moved around with the caster's wand acting as a navigator.