Adjectives

(s)precarious, unstableaffording no ease or reassurance“a precarious truce”
(s)parlous, perilous, precarious, touch-and-gofraught with danger“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”
(s)precarious, shakynot secure; beset with difficulties“a shaky marriage”