From Longman Dictionary of Contemporary Englishcustomscustoms[plural] a) the place where your bags are checked for illegal goods when you go into a country → immigration She was stopped at customs and questioned. It took ages to clear customs (=be allowed through customs) but then we were out of the airport quite quickly. You won’t be able to take that through customs. b) the government department that checks goods coming into a country and collects any taxes on them customs officers the US customs service → custom
Examples from the Corpus
customs• All bags must be inspected by customs officers.From Longman Business DictionaryCustomsCus‧toms /ˈkʌstəmz/ (also customs) noun [uncountable]ORGANIZATIONS1the government department responsible for collecting the tax on goods that have been brought into the country and making sure that illegal goods are not imported or exportedThe shipment had come from Spain and had been tracked by Customs.The pornographic photos, films and books have been seized by Customs officers.2the place at an airport or port through which people and goods arriving in a country must pass and where any tax owed must be paidIf you go over the limit you have to pay duty when you go through customs.The balance will be paid only after goods have cleared customs (=been checked by customs officials). 