moderately cold; neither warm nor cold

a rather cool evening.

feeling comfortably or moderately cold

I'm perfectly cool, but open the window if you feel hot.

imparting a sensation of moderate coldness or comfortable freedom from heat

a cool breeze.

permitting such a sensation

a cool dress.

not excited; calm; composed; under control

to remain cool in the face of disaster.

not hasty; deliberate

a cool and calculated action.

lacking in interest or enthusiasm

a cool reply to an invitation.

lacking in warmth or cordiality

a cool reception.

calmly audacious or impudent

a cool lie.

aloof or unresponsive; indifferent

He was cool to her passionate advances.

unaffected by emotions; disinterested; dispassionate

She made a cool appraisal of all the issues in the dispute.

Informal . (of a number or sum) without exaggeration or qualification

a cool million dollars.

(of colors) with green, blue, or violet predominating.

Slang .

great; fine; excellent

a real cool comic.

characterized by great facility; highly skilled or clever

cool maneuvers on the parallel bars.

socially adept

It's not cool to arrive at a party too early.

Informal . coolly.

something that is cool; a cool part, place, time, etc.

in the cool of the evening.

coolness.

calmness; composure; poise

an executive noted for maintaining her cool under pressure.

to become cool (sometimes fol. by down or off )

The soup cooled in five minutes. We cooled off in the mountain stream.

to become less ardent, cordial, etc.; become moderate.

to make cool; impart a sensation of coolness to.

to lessen the ardor or intensity of; allay; calm; moderate

Disappointment cooled his early zealousness.

cool down, to bring the body back to its normal physiological level after fast, vigorous exercise or activity by gradually slowing the pace of activity or by doing gentle exercises or stretches.

cool off, Informal . to become calmer or more reasonable

Wait until he cools off before you talk to him again.

cool out, Slang . to calm or settle down; relax

cooling out at the beach.

blow one's cool. blow 2 ( def. 43 ) .

cool it

Slang . calm down; take it easy.

cool one's heels. heel 1 ( def. 26 ) .