cool

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Neither warm nor very cold; moderately cold.
• adjective Giving or suggesting relief from heat.
• adjective Marked by calm self-control.
• adjective Marked by indifference, disdain, or dislike; unfriendly or unresponsive.
• adjective Of, relating to, or characteristic of colors, such as blue and green, that produce the impression of coolness.
• adjective Knowledgeable or aware of the latest trends or developments.
• adjective Excellent; first-rate.
• adjective Acceptable; satisfactory.
• adjective Slang Entire; full.
• adverb Informal In a casual manner; nonchalantly.
• intransitive verb To make less warm.
• intransitive verb To make less ardent, intense, or zealous.
• intransitive verb Physics To reduce the molecular or kinetic energy of (an object).
• intransitive verb To become less warm.
• intransitive verb To become calmer.
• noun A cool place, part, or time.
• noun The state or quality of being cool.
• noun Composure; poise.
• idiom (cool it) To calm down; relax.
• idiom (cool it) To stop doing something.
• idiom (cool (one's) heels) To wait or be kept waiting.

from The Century Dictionary.

• In painting, to strengthen (colors) on the blue and violet side of the spectrum, or to reduce (reds and yellows).
• To make cool or cold; reduce the temperature of: as, ice cools water.
• To allay the warmth or heated feeling of; impart a sensation of coolness to; cause to feel cool.
• To abate the ardor or intensity of; allay, as passion or strong emotion of any kind; calm, as anger; moderate, as desire, zeal, or ardor; render indifferent.
• To mitigate.
• To become cool; become less hot; lose heat.
• To lose the heat of excitement, passion, or emotion; become less ardent, angry, zealous, affectionate, etc.; become more moderate.
• noun A moderate or refreshing state of cold; moderate temperature of the air between hot and cold.
• Moderately cold; being of a temperature neither warm nor very cold: as, cool air; cool water.
• Having a slight or not intense sensation of cold. See cold, a., 3.
• Not producing heat or warmth; permitting or imparting a sensation of coolness; allowing coolness, especially by facilitating radiation of heat or access of cool air, or by intercepting radiated heat: as, a cool dress.
• In figurative uses:
• Not excited or heated by passion of any kind; without ardor or visible emotion; calm; unmoved: as, a cool temper; a cool lover.
• Not hasty; deliberate: as, a cool purpose.
• Manifesting coldness, apathy, or dislike; chilling; frigid: as, a cool manner.
• Quietly impudent, defiant, or selfish; deliberately presuming: said of persons and acts.
• Absolute; without qualification; round: used in speaking of a sum of money, generally a large sum, by way of emphasizing the amount.
• Unconcerned, lukewarm, indifferent; cold-blooded, repellent
• noun An obsolete spelling of cole.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb To make cool or cold; to reduce the temperature of.
• transitive verb To moderate the heat or excitement of; to allay, as passion of any kind; to calm; to moderate.
• transitive verb [Colloq.] to dance attendance; to wait, as for admission to a patron's house.
• noun A moderate state of cold; coolness; -- said of the temperature of the air between hot and cold.
• adjective Moderately cold; between warm and cold; lacking in warmth; producing or promoting coolness.
• adjective Not ardent, warm, fond, or passionate; not hasty; deliberate; exercising self-control; self-possessed; dispassionate; indifferent.
• adjective Not retaining heat; light.
• adjective Manifesting coldness or dislike; chilling; apathetic.
• adjective Quietly impudent; negligent of propriety in matters of minor importance, either ignorantly or willfully; presuming and selfish; audacious.