Learner's definition of DEPARTMENT
1 : one of the major parts of a company, organization, government, or school
— abbreviation dept.
Your letter has been forwarded to our sales department.
When you get to the hospital, go directly to the X-ray department.
the country's energy department
the Department of Defense = the Defense Department
the county sheriff's department
the university's math and science departments
the department of modern languages
the college's athletic department
She joined the town's police department.
2 : an area in a store where a particular kind of product is sold
3 a : a subject or activity that a person is interested in or responsible for b often humorous — used to say that someone or something has or does not have a particular quality
She's sweet, but she's somewhat lacking in the intelligence department. [=she is not very intelligent]
He does pretty well in the looks department. [=he is attractive]
Both cars do well in the safety department. [=both cars are safe to drive]