Synonyms and related words :
dangerous, desultory, doubtful, dubious, fly-by-night, hazardous, infirm, insecure, insubstantial, irresponsible, perilous, precarious, provisional, questionable, risky, rocky, shaky, shifting, shifty, slippery, temporary, tentative, ticklish, tottery, treacherous, trustless, unassured, uncertain, undependable, unfaithworthy, unhealthy, unpredictable, unreliable, unsafe, unsolid, unsound, unstable, unsteadfast, unsteady, unsubstantial, unsure, untrusty