Countercurse

A spell that reverses a curse.

References from the canon

• On his first trip to Diagon Alley, Harry was drawn to the book Curses and Countercurses (Bewitch Your Friends and Befuddle Your Enemies with the Latest Revenges: Hair Loss, Jelly-Legs, Tongue- Tying and Much, Much More) by Professor Vindictus Viridian because he wanted to curse his cousin Dudley (PS5).
• After Draco put the Leg-Locker Curse on Neville Longbottom, Hermione reversed it with a countercurse (PS13).
• Snape "muttered" a countercurse when Quirrell tried to make him fall off during Harry's first Quidditch match (PS11,PS17).
• Lockhart bragged that he knew a countercurse to the Transmogrifian Torture, a spell which may not even exist (CS9).
• The Killing Curse has no countercurse according to the Fake Moody (GF14).
• Dolores Umbridge frowned on the teaching of countercurses (OP12), but Harry was able to teach Dumbledore's Army many of them in secret (OP25).
• James Potter performed the Full-Body Bind on classmate Severus Snape, then Lily Evans made him use the countercurse (OP28).
• After the return of Voldemort, a "complex array of countercurses" protected Hogwarts school, according to the Daily Prophet (HBP3)
• Hermione assumed that Dumbledore would privately teach Harry "powerful countercurses ... anti-jinxes" (HBP5). Instead, Harry was taught the history of Tom Riddle and Lord Voldemort, with an emphasis on Horcruxes (HBP23).
• The countercurse for Levicorpus is Liberacorpus, according to the Half-Blood Prince (HBP18).
• The countercurse for the cutting spell Sectumsempra is "an incantation that sounded almost like song." Snape performed it three times over Draco before the bleeding stopped and he could be taken to the Hospital Wing (HBP24).
• Aurors receive training in countercurses (DP2).