Banishing Charm

"They were supposed to be practising the opposite of the Summoning Charm today — the Banishing Charm. Owing to the potential for nasty accidents when objects kept flying across the room. Professor Flitwick had given each student a stack of cushions on which to practise, the theory being that these wouldn’t hurt anyone if they went off target. It was a good theory, but it wasn’t working very well. Neville’s aim was so poor that he kept accidentally sending much heavier things flying across the room — Professor Flitwick, for instance...he Banished a cushion with a sweep of his wand (it soared into the air and knocked Parvati’s hat off)."

- The Charms Class on the Banishing Charm

The Banishing Charm (Depulso) is the counter-charm to the Summoning Charm. As Accio summons objects to the caster, Depulso sends both objects and living things away. Unlike the Summoning Charm, which can summon specific objects from anywhere, the Banishing Charm banishes whatever the wand is aimed at.

History
Fourth year students studying Charms at Hogwarts School of Witchcraft and Wizardry learn this spell. Harry and his classmates practised this spell in their fourth year Charms class. Flitwick found himself being Banished around the room by Neville, whose aim wasn't very good.

Known practitioners

 * Ginny Weasley
 * Harry Potter
 * Hermione Granger
 * Neville Longbottom
 * Ron Weasley
 * Sirius Black
 * Filius Flitwick
 * Severus Snape

Behind the scenes

 * Although the incantation is not revealed in the books, it appears in the video game adaptation of.
 * The Wizard in the The Wizard and the Hopping Pot may have used this spell to try to force the pot out of the house.
 * Although this spell is learned by Hogwarts students in their fourth year, in the video game adaptation of, Harry, Ron, and Hermione, were able to use it. It is possible that they learned it before that, as Hermione asked them, if they remembered it. However Hermione may have read beforehand and told Harry and Ron how to use it.

Etymology
From the Latin “depulsio”, meaning “driving/pushing away”. Also is similar to repulse meaning "drive/push away with force", although this is a precise antonym to attract, literally "pull towards". It could also be seen to be derived from the English word pulse (as in a pulse of energy) and the prefix "de" which would make it mean "a negative pulse of energy."

Notes and references
Depulso Sortilège d'Expulsion Depulso