Synonyms and related words :
alarming, bad, chance, chancy, critical, dangersome, desultory, explosive, fell, fraught with danger, grievous, hairy, haphazard, harmful, hazardous, hit-or-miss, iffy, infirm, insecure, insubstantial, jeopardous, major, menacing, parlous, periculous, perilous, precarious, provisional, random, rickety, risky, serious, shaky, shifting, shifty, slippery, temporary, tentative, threatening, ticklish, treacherous, ugly, uncertain, undependable, unfaithworthy, unhealthy, unreliable, unsafe, unsolid, unsound, unstable, unsteadfast, unsteady, unsubstantial, unsure, untrustworthy, wicked