That which makes smooth; varnish.
"The old wooden table was coated in a sleek layer of varnish to make its surface perfectly smooth."
In plain English: A sleek is not actually a word used as a noun, so it has no meaning in that form because people only use it to describe something smooth and stylish.
"The sleek was spotted swimming gracefully near the shore."
To make smooth or glossy; to polish or cause to be attractive.
"She used a special cream to sleek her hair until it shone brightly in the sunlight."
In plain English: To sleek something means to smooth it out so that its surface becomes shiny and free of bumps.
"The cat sleeked down its fur after rolling in the grass."
well-groomed and neatly tailored; especially too well-groomed
"sleek figures in expensive clothes"
designed or arranged to offer the least resistant to fluid flow
"a streamlined convertible"
Having an even, smooth surface; smooth
"The sleek surface of the polished marble reflected the sunlight perfectly."
In plain English: Sleek means smooth and shiny looking, often with a stylishly modern appearance.
"The sleek black car glided smoothly down the highway."
Usage: Use sleek as an adjective to describe objects with a polished, shiny appearance that suggests speed and elegance, such as a black car or modern furniture. Avoid confusing it with words like "rough" when describing texture, but note that the term implies both visual glossiness and functional smoothness rather than just being plain or unadorned.
With ease and dexterity.
"The magician performed the trick with such sleek movements that the audience barely noticed his hands moving at all."
Sleek is a later form of the word slick that shares roots with the German verb for "to creep" and the Dutch word for mud or slime. The term entered English to describe something smooth and shiny, evolving from its original association with slippery surfaces like wet ground.