(a.) Depending on some uncertain contingency; as, an aleatory contract.

Nachtmusik absolute music accidental adaptation adventitious adventurous air varie aleatoric aleatory music amorphous arrangement blobby blurred blurry broad casual causeless chamber music chamber orchestra chance chancy chaotic circumstantial composition conditional confused contingent descant destinal dicey disordered electronic music etude exercise fatal fatidic fluky foggy fortuitous full of risk fuzzy general harmonization hazardous hazy hit-or-miss iffy ill-defined imprecise inaccurate inchoate incidental incidental music incoherent indecisive indefinable indefinite indeterminable indeterminate indistinct inessential inexact instrumental music invention lax loose nocturne nonessential nonspecific obscure occasional opus orchestration orderless piece production program music provisional random ricercar riskful risky score shadowed forth shadowy shapeless sonata sonatina speculative stochastic string orchestra string quartet study sweeping theme and variations trio uncaused unclear undefined undestined undetermined unessential unexpected unforeseeable unforeseen unlooked-for unplain unpredictable unspecified vague variation veiled venturesome venturous wildcat work