motherfucking /ˈmʌðə(ɹ)ˌfʌkɪŋ/adjective 1adverb 1 adjective1 •(slang, vulgar) An intensifier, used in the same contexts as fucking, but more intense.America, fuck yeah! / Comin' again to save the motherfuckin' day, yeah! — 2004 adverb1 •(slang, vulgar) To an extreme degree.He is one motherfucking mean dude.