Webster's Revised Unabridged Dictionary · 1913

Battalion

Battalion (bat*tal"yun; 106) , noun

[French bataillon, from Italian battaglione. See Battalia.]

1.
A body of troops; esp. a body of troops or an army in battle array. [archaic]
The whole battalion views. — Milton
2.
(Military) 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.

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 ({not transcribed}) , transitive verb

To form into battalions. [Rare]