101 Magical Spells: Words of Wizardry from the World of Harry Potter (Part 5: R-Z)

Reducio!
Word Origin: From the Latin reducere (to lead or bring back)
Purpose: This spell is a counter-incantation for the spell "Engorgement Charm" which enlarges objects. Reducio returns the object to its original size.
Example: In Harry Potter and the Goblet of Fire, after enlarging a spider using the Engorgement Charm, the fake Moody uses this spell to return it to its normal size.

Rennervate!
Word Origin: From the Latin Re (Again) and enerver (new) = to make new again
Purpose: This spell is used to revive a person who has passed out or been rendered unconscious
Example: In Harry Potter and the Goblet of Fire, Amos Diggory revived the Stunned Winky with this spell.

Reparo!
Word Origin: From the Latin reparare (restore, put back in order)
Purpose: This spell is used to fix broken objects
Example: In Harry Potter and the Order of the Phoenix, Snape cast this spell during Occlumency class, to repair a jar that shattered in his office.

Rictusempra!
Word Origin: From the Latin Rictus (wide-open mouth) and semper (always)
Purpose: This is the incantation for the Tickling Charm, which causes the victim to laugh uncontrollably. When it is cast, a bolt of silver light issues from the caster's wand and hits the victim, causing the uncontrollable laughter. The spell "Finite Incanatem!" can be used to counter the effects of this charm.
Example: In Harry Potter and the Chamber of Secrets, Harry used this spell on Draco at the Duelling Club.

Riddikulus!
Word Origin: From the Latin ridiculus (facetious, laughable)
Purpose: This incantation is used to get rid of a Bogart - a creature that assumes the form of a person's greatest fear. Prior to casting the spell, the wizard/witch must visualize the Bogart doing or being something humorously ridiculous. The laughter this causes will banish the Boggart
Example: In Harry Potter and the Goblet of Fire, while in the Triwizard maze, Harry successfully cast this spell upon a boggart