1. 1. An army unit typically consisting of a headquarters and two or more companies, batteries, or similar subunits.
   2. A large body of organized troops.
2. A great number: battalions of ants.

[French bataillon, from Old French, from Italian battaglione, augmentative of battaglia, from Vulgar Latin *battalia. See battle.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.