Source : Webster's Revised Unabridged Dictionary (1913)

Defensive \De*fen"sive\, a. [Cf. F. d['e]fensif.]
   1. Serving to defend or protect; proper for defense; opposed
      to offensive; as, defensive armor.

            A moat defensive to a house.          --Shak.

   2. Carried on by resisting attack or aggression; -- opposed
      to offensive; as, defensive war.

   3. In a state or posture of defense. --Milton.

Defensive \De*fen"sive\, n.
   That which defends; a safeguard.

         Wars preventive, upon just fears, are true defensives.
                                                  --Bacon.

   {To be on the defensive}, {To stand on the defensive}, to be
      or stand in a state or posture of defense or resistance,
      in opposition to aggression or attack.

Source : WordNet®

defensive
     n : an attitude of defensiveness (especially in the phrase `on
         the defensive') [syn: {defensive attitude}]

defensive
     adj 1: intended or appropriate for defending against or deterring
            aggression or attack; "defensive weapons"; "a
            defensive stance" [ant: {offensive}]
     2: attempting to justify or defend in speech or writing [syn: {justificative},
         {justificatory}]
     3: serving as or appropriate for defending or protecting;
        "defensive fortifications"; "defensive dikes to protect
        against floods"