1 : an action or way of behaving that is usual and traditional among the people in a particular group or place [count] ▪ tribal/local/family/ancient customs ▪ social customs ▪ an English/Indian custom ▪ It is the custom for the bride to wear a white dress on her wedding day. [noncount] ▪ According to custom, the festivities begin at dusk. ▪ It's a matter of custom. 2 [singular] : something that is done regularly by a person
▪ She had breakfast in bed, as was her custom. [=habit] 3 customs [plural] a : taxes or fees that are paid to the government when goods come into or go out of a country — often used before another noun ▪ customs duties
b : the place at an airport, border, etc., where government officers collect customs on goods and look for things that people are trying to bring into a country illegally
▪ We went through customs at the airport without any difficulty. ▪ It took us a long time to clear customs at the border. — often used before another noun ▪ a customs agent/officer/inspector 4 [noncount] Brit, formal : the practice of regularly going to the same shop or business to buy things or services
▪ As new shops have opened people have been taking their custom [=business] elsewhere.