The noun army has 3 senses (first 2 from tagged texts)
1. (61) army, regular army, ground forces -- (a permanent organization of the military land forces of a nation or state)
2. (2) army -- (a large number of people united for some specific purpose)
3. United States Army, US Army, U. S. Army, Army, USA -- (the army of the United States of America; the agency that organizes and trains soldiers for land warfare)