fraught with danger; "dangerous waters"; "a parlous journey on stormy seas"; "a perilous voyage across the Atlantic in a small boat"; "the precarious life of an undersea diver"; "dangerous surgery followed by a touch-and-go recovery"
Held by a doubtful tenure; depending on unknown causes or events; exposed to constant risk; not to be depended on for certainty or stability; uncertain; as, a precarious state of health; precarious fortunes.