Merriam-Webster Collegiate Dictionary - defensive

 I. adjective  Date: 14th century  1. serving to defend or protect ~ fortifications  2.  a. devoted to resisting or preventing aggression or attack ~ behavior  b. of or relating to the attempt to keep an opponent from scoring in a game or contest a player with good ~ skills  3.  a. valuable in ~ play a ~ card in bridge  b. designed to keep an opponent from being the highest bidder a ~ bid  • ~ly adverb  • ~ness noun  II. noun  Date: 1601 a ~ position