Subdepartment

noun
1.
a distinct part of anything arranged in divisions; a division of a complex whole or organized system.
2.
one of the principal branches of a governmental organization:
the sanitation department.
3.
(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.
4.
a division of a business enterprise dealing with a particular area of activity:
the personnel department.
5.
a section of a retail store selling a particular class or kind of goods:
the sportswear department.
6.
one of the sections of a school or college dealing with a particular field of knowledge:
the English department.
7.
one of the large districts into which certain countries, as France, are divided for administrative purposes.
8.
a division of official business, duties, or functions:
judicial departments.
9.
a sphere or province of activity, knowledge, or responsibility:
Paying the bills is not my department.
10.
(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.
noun
1.
a specialized division of a large concern, such as a business, store, or university: the geography department
2.
a major subdivision or branch of the administration of a government
3.
a branch or subdivision of learning: physics is a department of science
4.
a territorial and administrative division in several countries, such as France
5.
(informal) a specialized sphere of knowledge, skill, or activity: wine-making is my wife’s department