1 adjective - done or operating in an impressively smooth and efficient way.
2 glibly assured.
3 (of skin or hair) smooth and glossy. 4 (of a surface) smooth, wet, and slippery, noun a smooth patch of oil, especially on the sea.
4 verb - 1 make (hair) flat and slick with water, oil, or cream.
5 (slick up) N. Amer. make smart, tidy, or stylish.
— DERIVATIVES slickly adverb slickness noun.
— ORIGIN probably related to an Old Norse word meaning ‘smooth’.
in Compact Oxford English Dictionary