Confundus Charm

The Confundus Charm is a charm that causes a person or animated object to become highly confused. There appears to be varying degrees of inflicted confusion, ranging from tricking a person about a specific issue to making them lose all semblance of common sense, even to the point of endangering themselves. The incantation is "Confundo."

Known Uses

 * During the Triwizard Tournament of 1994, Barty Crouch, Jr. (in the disguise of retired Auror and new Defence Against the Dark Arts professor Alastor Moody) used this charm to fool the Goblet of Fire into accepting Harry Potter under a non-existent fourth school.
 * In 1996, Hermione Granger used this spell on Cormac McLaggen during the Gryffindor Quidditch team's Keeper tryouts to lessen his chances of passing after she overheard him insult Ron and Ginny Weasley.
 * In 1997, under Dumbledore's portrait's instructions, Severus Snape used this charm on Mundungus Fletcher, so that the latter could suggest using seven identical Potters (by means of the Polyjuice Potion) to the other members of the Order of the Phoenix when they moved Harry from Privet Drive.
 * In 1998, Harry used the Confundus Charm on several employees of Gringotts Wizarding Bank in order to facilitate a break-in.
 * In 2017, Ron used this spell on a Muggle driving instructor to earn his driving-license.

Possible Uses

 * The Confundus Charm may be the spell that Ron Weasley was struck with by a Death Eater during the Battle of the Department of Mysteries. He was highly confused and inappropriately amused, even summoning brains to himself, which subsequently began to strangle him.
 * In 1938, Albus Dumbledore may have used the Confundus Charm on Mrs. Cole; since the latter did not seem to facilitate Dumbledore's attempt to take Tom Marvolo Riddle to Hogwarts, and was said to be an "inconveniently sharp woman," Dumbledore waved his wand and showed her a blank piece of paper, and her eyes went briefly out of focus. She then let Dumbledore take Riddle without further questions, saying the blank paper was "perfectly in order." (However, Dumbledore's showing her the blank piece of paper may have simply been to distract her as he conjured a bottle of mead and two glasses, and her eyes may have gone out of focus because of staring at a piece of paper that she expected to "clear things up", and finding it blank. Her subsequent willingness to let Dumbledore take Riddle may have been due to the fact that she was somewhat inebriated and also did not enjoy Riddle's presence in the orphanage.)

Etymology
Confundus, as well as the incantation confundo, may be derived from the Latin verb confundere, "to confuse, to perplex." They could also be derived from the English word "confound." Confundo means "I confuse" in Portuguese.

Behind the scenes

 * In the video games and film, the incantation is Confundus.
 * In Harry Potter and the Prisoner of Azkaban, Severus Snape insisted that the reason that Harry Potter and Ronald Weasley stated that Sirius Black was innocent was because Black had used this Charm on them.

Appearances

 * Harry Potter and the Prisoner of Azkaban
 * Harry Potter and the Goblet of Fire
 * Harry Potter and the Goblet of Fire (film)
 * Harry Potter and the Goblet of Fire (video game)
 * Harry Potter and the Half-Blood Prince
 * Harry Potter and the Half-Blood Prince (film)
 * Harry Potter and the Deathly Hallows
 * Harry Potter and the Deathly Hallows: Part 1 (video game)
 * Harry Potter: Spells

Notes and references
Sortilège de Confusion