The Knockback Jinx is a jinx that enables the caster to "knock back" objects or people. Its incantation is Flipendo. It first appeared in the video game adaptation of Harry Potter and the Philosopher's Stone, and has appeared in almost every Harry Potter videogame after that, as well as in Pottermore.
This spell is not used nor mentioned in the books.
The Knockback Jinx is one of the spells that can be used on a wizard's duel in Pottermore. The spell was first confirmed as canon on its inclusion in it, almost 10 years after its introduction in an unofficial capacity in the videogame adaptation of Philosopher's Stone.
This spell is not used nor mentioned in the films.
Being first introduced in the Philosopher's Stone videogame, this spell has been prominent in almost all videogames since. It has appeared in the videogame adaptations of the first six books and films, as well as in Lego Harry Potter: Years 1-4.