convex lens n.
A lens having at least one surface that curves outward like the exterior of a sphere.
- Cool britannia
noun the fashionable London scene Word Origin a pun on the song Rule Britannia
adjective pertaining to burning at a low temperature Examples Always choose cool-burning decorative lights for a Christmas tree. Word Origin 1843
- Cool cat
noun a stylish and admirable person Usage Note slang noun A stylish and admirable person
- Cool colors
noun the blues and greens of the color spectrum, associated with water, sky, ice, and cooler temperatures; also called cold colors Examples Bluish grays are referred to as cool colors.