moth·er·fuck·er /ˈmʌðəˌfʌkə $ -ðərˌfʌkər/ noun [countableC]American EnglishAmE 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. 混賬東西,雜種 —motherfucking adjectiveadj