In
military science, defense (or defence) is the art of preventing an attack, or minimizing the damage of an attack, e.g. by preventing an enemy from conquering
territory.Thus, if a party attacks an enemy who is about to attack that party, this could be called defense. However, this leaves room for interpretation.Typically defensive are e.g.
armor and a
bunker. Also defensive are guns, rockets, etc. with a range within the defenders territory: they can only attack an attacker. If the weapon is mobile it may also be used in an attack, after moving it.
See more at Wikipedia.org...