Definition of: cool

(kl) adjective
1. Moderate in temperature; not warm; some what cold.
2. Serving to produce or giving the effect of coolness.
3. Self-controlled; self-possessed.
4. Indifferent; chilling; slighting.
5. Audacious; impudent.
6. Colloq. Actual; absolute; not exaggerated: a cool million dollars.
7. Art Suggesting a sense of coolness: said of the colors blue, green, and violet.
8. Slang Very good; well done. See synonyms under CALM, FRESH.
—v.t.
1. To lower the temperature of; make cooler or less hot.
2. To render less excited or excitable: allay, as passion; calm; moderate.
—v.i.
3. To become cool or less hot.
4. To lose the heat of excitement or passion; become less ardent, angry, zealous, or affectionate.
—to cool it Slang To calm down; take it easy.
—to cool one's heels To wait long and wearily in attendance.
—noun
1. A moderate temperature approaching cold: the cool of the day.
2. That which is cool.
3. Slang Calm detachment; composure.
—to blow one's cool Slang To get excited; become emotional. [OE col]
—cool′ish adjective
—cool′ly adverb
—cool·ness noun