depending on the throw of a dice or on chance; random.
relating to or denoting music or other forms of art involving elements of random choice (sometimes using statistical or computer techniques) during their composition, production, or performance:aleatory musica photograph can capture the aleatory chaos of modern urban life
late 17th century: from Latin aleatorius, from aleator 'dice player', from alea 'die', + -y1
aleatory in other Oxford dictionaries
Definition of aleatory in the US English dictionary