a distinct part of anything arranged in divisions; a division of a complex whole or organized system.

one of the principal branches of a governmental organization

the sanitation department.

( initial capital letter ) one of the principal divisions of the U.S. federal government, headed by a Secretary who is a member of the President's cabinet.

a division of a business enterprise dealing with a particular area of activity

the personnel department.

a section of a retail store selling a particular class or kind of goods

the sportswear department.

one of the sections of a school or college dealing with a particular field of knowledge

the English department.

one of the large districts into which certain countries, as France, are divided for administrative purposes.

a division of official business, duties, or functions

judicial departments.

a sphere or province of activity, knowledge, or responsibility

Paying the bills is not my department.

( usually initial capital letter ) U.S. Army . (formerly) a large geographical division of the U.S. or its possessions as divided for military and defense purposes

the Hawaiian Department.