From Longman Dictionary of Contemporary Englishmotherfuckermoth‧er‧fuck‧er /ˈmʌðəˌfʌkə $ -ðərˌfʌkər/ noun [countable] American English taboo spokenDON'T LIKEINSULT a very offensive word for someone that you dislike very much or that you are very angry with. Do not use this word. —motherfucking adjective