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