Aleatory music (from Lat. alea, dice; hence the throw of the dice for chance). Synonym for indeterminacy, i.e. mus. that cannot be predicted before perf. or mus. which was comp. through chance procedures (statistical or computerized). The adjective 'aleatoric' is a bastard word, to be avoided by those who care for language.
Gee. I'll never use that bastard word again.