Source : Webster's Revised Unabridged Dictionary (1913)

Militant \Mil"i*tant\, a. [L. militans, -antis, p. pr. of
   militare to be soldier: cf. F. militant. See {Militate}.]
   Engaged in warfare; fighting; combating; serving as a
   soldier. -- {Mil"i*tant*ly}, adv.

         At which command the powers militant . . . Moved on in
         silence.                                 --Milton.

   {Church militant}, the Christian church on earth, which is
      supposed to be engaged in a constant warfare against its
      enemies, and is thus distinguished from the church
      triumphant, in heaven.

Source : WordNet®

militant
     adj 1: engaged in war; "belligerent (or warring) nations"; "a
            fighting war" [syn: {belligerent}, {fighting}, {war-ridden},
             {warring}]
     2: showing a fighting disposition without self-seeking; "highly
        competitive sales representative"; "militant in fighting
        for better wages for workers"; "his self-assertive and
        ubiquitous energy" [syn: {competitive}]
     n : a militant reformer [syn: {activist}]