smegmaPronunciation: /ˈsmɛgmə/Definition of smegma noun [mass noun] a sebaceous secretion in the folds of the skin, especially under a man’s foreskin. Origin: early 19th century: via Latin from Greek smēgma 'soap', from smēkhein 'cleanse'smegma in other Oxford dictionaries Definition of smegma in the US English dictionary