1. Prudent
   "guarded optimism";
   - restrained

1. Watch over or shield from danger or harm; protect
   "guard my possessions while I'm away";
   - ward
    
2. To keep watch over
   "there would be men guarding the horses"
    
3. Protect against a challenge or attack
   "guard that position behind the trees!";
   - defend, hold
    
4. Take precautions in order to avoid some unwanted consequence
   "guard against becoming too friendly with the staff"; "guard against infection"

See also: cautious

Type of: act, follow, keep an eye on, move, observe, protect, watch, watch over

Encyclopedia: Guarded