adventurous, aleatory, chancy, dangerous, desultory, dicey, dickey, fraught with danger, full of risk, hairy, infirm, insecure, insubstantial, jeopardous, parlous, perilous, precarious, provisional, questionable, riskful, risky, shaky, shifting, shifty, slippery, speculative, temporary, tentative, ticklish, treacherous, tricky, uncertain, undependable, unfaithworthy, unhealthy, unpredictable, unreliable, unsafe, unsolid, unsound, unstable, unsteadfast, unsteady, unsubstantial, unsure, untrustworthy, venturesome, venturous, wicked, wildcat