The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

         At which command the powers militant . . .
         Moved on in silence.                     --Milton.
   [1913 Webster]

   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.
      [1913 Webster]