Source : Webster's Revised Unabridged Dictionary (1913)

Battalion \Bat*tal"ion\, n. (Mil.)
   An infantry command of two or more companies, which is the
   tactical unit of the infantry, or the smallest command which
   is self-supporting upon the battlefield, and also the unit in
   which the strength of the infantry of an army is expressed.

   Note: In the United States army, since April 29, 1898, a
         battalion consists of four companies, and three
         battalions form a regiment. The term is also applied to
         two or more batteries of artillery combined into a
         single command.

Battalion \Bat*tal"ion\, n. [F. bataillon, fr. It. battaglione.
   See {Battalia}.]
   1. A body of troops; esp. a body of troops or an army in
      battle array. ``The whole battalion views.'' --Milton.

   2. (Mil.) A regiment, or two or more companies of a regiment,
      esp. when assembled for drill or battle.

Battalion \Bat*tal"ion\, v. t.
   To form into battalions. [R.]

Source : WordNet®

battalion
     n 1: an army unit usually consisting of a headquarters and three
          or more companies
     2: a large indefinite number; "a battalion of ants"; "a
        multitude of TV antennas"; "a plurality of religions"
        [syn: {large number}, {multitude}, {plurality}, {pack}]