ambiguous, borderline, chancy, critical, dangerous, delicate, desultory, dicey, difficult, doubtful, dubious, equivocal, hairy, hazardous, iffy, indecisive, infirm, insecure, insubstantial, on slippery ground, on thin ice, open, perilous, problematic, provisional, questionable, risky, sensitive, shaky, shifting, shifty, slippery, slippy, temporary, tentative, ticklish, touch-and-go, touchy, treacherous, tricky, uncertain, undependable, unfaithworthy, unpredictable, unreliable, unsettled, unsolid, unsound, unstable, unsteadfast, unsteady, unsubstantial, unsure, untrustworthy