The Collaborative International Dictionary of English v.0.48:

Defender \De*fend"er\ (d[-e]*f[e^]nd"[~e]r), n. [Cf. Fender.]
   One who defends; one who maintains, supports, protects, or
   vindicates; a champion; an advocate; a vindicator.
   [1913 Webster]

         Provinces . . . left without their ancient and puissant
         defenders.                               --Motley.
   [1913 Webster]

WordNet (r) 3.0 (2006):

defender
    n 1: a person who cares for persons or property [syn:
         defender, guardian, protector, shielder]
    2: a fighter who holds out against attack [syn: defender,
       withstander]