A smooth, waterproof raincoat, usually made of oilcloth or plastic; also an adjective meaning smoother or more clever and deceptive.
From 'slick' meaning smooth or glossy, plus the comparative suffix '-er.' Originally referred to waterproof clothing used by sailors and outdoor workers in the 19th century.
The word 'slicker' captures how smooth, polished things can be either genuinely useful (a raincoat) or deceptively attractive (a slick salesman)—English perfectly balances the practical and the suspicious.
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