sleek: [16] Sleek originated as a variant form of slick [14], which probably went back to an unrecorded Old English *slice. It apparently has relatives in Icelandic slíkja and Norwegian slikja ‘smoothen’. => slick[sleek etymology, sleek origin, 英语词源]
1580s, variant of Middle English slike (see slick (adj.)). Originally of healthy-looking animal hair; applied to persons 1630s, with sense of "plump and smooth-skinned." Figurative meaning "slick, fawning, flattering" is from 1590s.