Learner's definition of ARMY
a large group of soldiers organized to fight battles on land
the part of a country's military forces that includes soldiers who are trained to fight on land
— usually capitalized when a specific army is being referred to
the U.S. Army, Navy, Air Force, and Marines
She's in the British Army.
— often used before another noun
a large number of people or things that are involved in some activity together
see also salvation army
The company employs an army of lawyers to handle its legal affairs.
They sent in a whole army of trained technicians.
an army of ants
The organization was founded by a dedicated army of volunteers.