department

noun

• A part, portion, or subdivision.
• A distinct course of life, action, study, or the like.

  "Technical things are not his department; he's a people person."

• A subdivision of an organization.
• A territorial division; a district; especially, in France, one of the districts into which the country is divided for governmental purposes, similar to a county in the UK and in the USA. France is composed of 101 départements organized in 18 régions, each department is divided into arrondissements, in turn divided into cantons.
• A military subdivision of a country

  "the Department of the Potomac"

• Act of departing; departure.