Aleatory (or aleatoric) means "pertaining to luck". Aleatoric art is that which exploits the principle of randomness. One of the most ambitious aleatory projects in poetry is Raymond Queneau's Cent Mille Milliards de Poèmes (Hundred Thousand Billion Poems).

John Cage was a very important name in aleatoric music, a well known form of aleatory. In 4′ 33″, he sits at the piano for four minutes and thirty-three seconds and the reactions of the audience (whispering, coughs, laughs ...) form the music.