Synonyms and related words :
accidental, adventitious, adventurous, agnostic, aleatory, ambiguous, capricious, casual, causeless, chance, chancy, changeable, contingent, dangerous, destinal, difficult, doubtful, doubting, equivocal, erratic, fatal, fatidic, fickle, fluky, fortuitous, full of risk, hairy, hazardous, hesitant, hesitating, iffy, incalculable, incidental, indecisive, indemonstrable, indeterminate, irresolute, polysemous, riskful, risky, skeptical, speculative, ticklish, touch-and-go, tricky, unaccountable, uncaused, uncertain, unconfirmable, unconvinced, undetermined, undivinable, unexpected, unforeseeable, unforeseen, unlooked-for, unpersuaded, unpredictable, unprovable, unsure, unverifiable, variable, venturesome, venturous, wavering, whimsical, wildcat,