I'd use it as an adjective to describe something that looks "sharp," "futuristic," "stream-lined," or "new."
Example:
That new Porsche looks so sleek and shiny.
The design for the new X-box is more sleek and much thinner than the previous model.
Me and my hair are sleek today.
Here is an example sentence with the word "sleek":Melissa groomed her horse until its coat was sleek and shiny.
The sports car had a sleek, aerodynamic design.
The machine looked sleek with a high build quality
sleek and agile as a gymnast
The boy wasn't fat, he was sleek. Jim admired the sleek lines of the newest model Jaguar.
A sentence using catnip is:When I go to the pet store, I always buy the best, healthiest catnip for my sleek cat
Here is an example sentence with the word "beautiful":The Afghan Hound is a beautiful breed of dog with its sleek coat and elegant build.
The cat was sleek and slim as he wound his way through the house.
Futuristic is an adjective that is used to describe something that looks sleek and modern, or that it may be from the future. A sentence using the word could be: "With the way the chrome on his car sparkled, Jerry thought it looked pretty futuristic."
Sleek and gracefuf
Sleek only has one syllable.