WordWeb Online

1. Lacking in security or safety
   "his fortune was increasingly unsafe";
   - insecure
    
2. Involving or causing danger or risk; liable to hurt or harm
   - dangerous
    
3. Not safe from attack
   - insecure

Derived forms: unsafer, unsafest

See also: breakneck, chanceful [archaic], chancy, desperate, dicey, dodgy [Brit, informal], hazardous, insidious, mordacious, on the hook, out on a limb, parlous, perilous, precarious, risky, self-destructive, shaky, suicidal, touch-and-go, treacherous, unguaranteed, unprotected, unreliable, unsecured, vulnerable, wild

Antonym: safe, secure