perilous

adj

dangerous, fraught with danger, hazardous, chancy, jeopardous, Archaic. parlous, risky, venturesome; treacherous, deceptive, unreliable, untrustworthy, sneaky; threatening, menacing, minatory, minacious; building up, impending, looming, ominous, inauspicious, unfavorable, boding ill; scary, Sl. hairy, dire, frightening, disquieting, Inf. spooky, eerie; desperate, urgent, with no escape, without a parachute, past the point of no return, in no-man's land, caught in the crossfire; exposed, unsheltered, out in the open, vulnerable, defenseless, with no place to hide; precarious, shaky, tottery, rickety, about to go, on its last legs, unstable, unsteady, unsound, unsafe, unhealthy; delicate, ticklish, touchy, thorny, difficult, critical.