custom

noun | cus·tom

1. : a practice common to many or to a particular place or institution; especially : a long-established practice that is generally recognized as having the force of law — see also section 1983 — compare usage : a long-established practice that is generally recognized as having the force of law — see also section 1983 — compare usage

   a : duties, tolls, or imposts imposed by the law of a country on imports or exports

   b : the agency, establishment, or procedure for collecting such customs