Noah Webster's New International Dictionary of the English Language

1. (superl.) Having an even, smooth surface; smooth; hence, glossy; as, sleek hair.

2. (superl.) Not rough or harsh.

3. (adv.) With ease and dexterity.

4. (n.) That which makes smooth; varnish.

5. (v. t.) To make even and smooth; to render smooth, soft, and glossy; to smooth over.