1. Fraught with danger
   "the precarious life of an undersea diver";
   - parlous, perilous, touch-and-go
    
2. Not secure; beset with difficulties
   "a precarious marriage";
   - shaky
    
3. Affording no ease or reassurance
   "a precarious truce";
   - unstable

See also: dangerous, insecure, uneasy, unsafe

Encyclopedia: Precarious