precarious

adj.
affording no ease or reassurance
a precarious truce
Synonyms: unstable
adj.
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
adj.
not secure; beset with difficulties
a shaky marriage
Synonyms: shaky