Source : Webster's Revised Unabridged Dictionary (1913)

Precautionary \Pre*cau"tion*a*ry\, a.
   Of or pertaining to precaution, or precautions; as,
   precautionary signals.

Source : WordNet®

precautionary
     adj : taken in advance to protect against possible danger or
           failure; "gave precautionary advice"; "I would take
           precautionary steps to keep him away" [syn: {precautional}]