of or at a fairly low temperature

it'll be a cool afternoon

the wind kept them cool

showing no friendliness towards a person or enthusiasm for an idea or project

he gave a cool reception to the suggestion for a research centre

fashionably attractive or impressive

he made no concessions to fashion, yet somehow he was hip and cool

I always wore sunglasses to look cool

used to emphasize the size of an amount of money

research for a new drug can cost a cool £50 million