de‧part‧ment S3 W1 [countable]
one of the groups of people who work together in a particular part of a large organization such as a hospital, university, company, or government:
the personnel department
the English department
the Department of the Environment
an area in a large shop where a particular type of product is sold:
the toy department
if something is someone's department, they are responsible for it or know a lot about it:
I'll see what I can do, but it's not really my department.
a particular part of someone's character, or a particular part of a larger activity or subject:
Dave was lacking in the trustworthiness department.
a departmental meeting