Old English smerian "to anoint or rub with grease, oil, etc.," from Proto-Germanic *smerthan (cf. Old Norse smyrva, Danish smøre, Swedish smörja, Dutch smeren, Old High German smirwen, German schmieren "to smear"), from PIE *smeru- "grease" (cf. Greek myron "unguent, balsam," Old Irish smi(u)r "marrow," Old English smeoru "fat, grease"). Sense of "assault a public reputation with unsubstantiated charges" is from 1879. Related: Smeared; smearing.