Wikipedia
Anti-genre is a self-descriptive label attributed to any artistic style devoid of genre. This lack of genre-status can either be the result of:
(1) an active attempt to evade categorization (transcend all genres),
(2) conscious negation of the ethos of its medium (unlearning of history),
(3) an active and conscious negation of itself.
The anti-genre is not simply an assault on tradition (previous artistic styles), for every anti-thesis in history would then fall under this title. (see Hard versus Soft section) The anti-genre, rather implies a more direct and nihilistic attack on the foundations of its medium. The anti-genre is in a perpetual state of evasion both from external taxonomy, but also from itself.
The artistic movement known as Dada is likely the best example of the anti-genre, although the Dada manifestos of Hugo Ball and Tristan Tzara never use the term 'anti-genre' to describe Dada,
DADA DOES NOT MEAN ANYTHING. Every man must shout: there is great destructive, negative work to be done. To sweep, to clean.
Dada means nothing... Thought is produced in the mouth.
The etymology of the term anti-genre borrows its semantic form from the terms anti- meaning against and genre, (French "kind," related to the English "gender")