• (England, Wales) enPR: ko͞ol, IPA: /kuːl/
• (Scotland) IPA: /kʉl/
• (America) IPA: /kul/

From Middle English cool, from Old English cōl, from Proto-West Germanic *kōl(ī), from Proto-Germanic *kōlaz, *kōluz, from Proto-Indo-European *gel-.

Cognate with Saterland Frisian köil, Western Frisian koel, Dutch koel, Limburgish kool, nds-de köhl, German kühl. Related to cold.

cool (comparative cooler, superlative coolest)

1. Of a mildly low temperature.

   Synonyms: chilly

   Antonyms: lukewarm, tepid, warm

   I like cool weather the most 'cause it's not too hot to wear a jacket but I won't be too cold in my shorts.

   • 1897 December (indicated as 1898), Winston Churchill, chapter VIII, in The Celebrity: An Episode, New York, N.Y.: The Macmillan Company; London: Macmillan & Co., Ltd., →OCLC ↗:

     The day was cool and snappy for August, and the Rise all green with a lavish nature. Now we plunged into a deep shade with the boughs lacing each other overhead, and crossed dainty, rustic bridges over the cold trout-streams, the boards giving back the clatter of our horses' feet: […] .

2. Allowing or suggesting heat relief.

   Linen has made cool and breathable clothing for millennia.

   • 1963, Margery Allingham, chapter 2, in The China Governess: A Mystery, London: Chatto & Windus, →OCLC ↗:

     Now that she had rested and had fed from the luncheon tray Mrs. Broome had just removed, she had reverted to her normal gaiety.  She looked cool in a grey tailored cotton dress with a terracotta scarf and shoes and her hair a black silk helmet.

3. Of a color, in the range of violet to green.

   Antonyms: warm

   If you have a reddish complexion, you should mainly wear cool colors.

4. (of a person) Not showing emotion; calm and in control of oneself.

   Synonyms: distant, phlegmatic, standoffish, unemotional

   Antonyms: passionate

   Be cool. There's no need to panic.

5. Unenthusiastic, lukewarm, skeptical.

   Antonyms: warm

   His proposals had a cool reception.

6. Calmly audacious.
   • 1868, Louisa M[ay] Alcott, chapter 13, in Little Women: […], part first, Boston, Mass.: Roberts Brothers, published 1869, →OCLC ↗:

     "Well, that's cool," said Laurie to himself, "to have a picnic and never ask me!"

7. Applied facetiously to a sum of money, commonly as if to give emphasis to the largeness of the amount.
   • 1749, Henry Fielding, The History of Tom Jones, a Foundling, volume (please specify |volume=I to VI), London: A[ndrew] Millar, […], →OCLC ↗:

     Who will lend me a cool hundred.

   • 1860 December – 1861 August, Charles Dickens, chapter XVIII, in Great Expectations […], volume III, London: Chapman and Hall, […], published October 1861, →OCLC ↗, page 303 ↗:

     But she had wrote out a little coddleshell in her own hand a day or two afore the accident, leaving a cool four thousand to Mr. Matthew Pocket.

   • 1900, Dora Sigerson Shorter, ''Transmigration

     You remember Bulger, don't you? You lost a cool hundred to him one night here over the cards, eh?

   • 1944 November 28, Irving Brecher and Fred F. Finklehoffe, Meet Me in St. Louis, Metro-Goldwyn-Mayer:

     My father was talking to the World's Fair Commission yesterday, and they estimate it's going to cost a cool fifty million.

8. (informal, of a person) Knowing what to do and how to behave; behaving with effortless and enviable style and panache; considered popular by others.

   Antonyms: awkward, uncool

9. (informal, originally, AAVE) Fashionable; trendy and hip.

   Synonyms: à la mode, fashionable, in fashion, modish, stylish, happening, hip, in, trendy

   Antonyms: démodé, old hat, out, out of fashion

   • 2008, Lou Schuler, "Foreward", in Nate Green, Built for Show, page xii

     The fact that I was middle-aged, bald, married, and raising girls instead of chasing them didn't really bother me. Muscles are cool at any age.

10. (informal) All right; acceptable.

    Synonyms: acceptable, all right, OK

    Antonyms: not cricket, not on, unacceptable

    Is it cool if I sleep here tonight?

11. (informal) Very interesting or exciting.

    I think astronomy is really cool.

    Synonyms: awesome, neat

12. (informal) (followed by with) Able to tolerate; to be fine with.

    I'm completely cool with my girlfriend leaving me.

    Synonyms: easy, fine, not bothered, not fussed

    Antonyms: bothered, upset

13. (informal) (of a pair of people) Having good relations.

    We're cool, right?

• French: frais
• German: kühl
• Italian: fresco, freddo
• Portuguese: fresco
• Russian: прохла́дный
• Spanish: fresco

• Italian: termico, fresco, leggero
• Portuguese: frio
• Spanish: frío

• German: cool, kalt
• Italian: tranquillo, calmo, imperturbabile, freddo
• Portuguese: tranquilo
• Russian: хладнокро́вный
• Spanish: tranquilo, sereno

• German: kühl
• Italian: distaccato, indifferente, scettico
• Portuguese: frio
• Russian: прохла́дный
• Spanish: apacible

• Italian: intrepido, fantastico
• Russian: де́рзкий

• German: cool
• Italian: figo, disinvolto, sicuro di se, in gamba
• Portuguese: fixe (Portugal), legal (Brazil), massa (Brazil)
• Russian: круто́й
• Spanish: estupendo, genial

• French: chouette
• German: cool, geil
• Italian: ganzo
• Portuguese: bacana, descolado
• Russian: круто́й
• Spanish: genial, guay (Spain), bacán, chévere (Slang-Latin America)

• French: cool
• German: cool
• Italian: figo
• Portuguese: descolado, bacana
• Russian: круто́й
• Spanish: guay

• French: cool
• German: in Ordnung, ganz Recht, alles klar, akzeptabel
• Italian: a posto, accettabile
• Portuguese: aceitável
• Russian: в поря́дке
• Spanish: bacán (Chile), bacano (Colombia), bárbaro (Argentina), bravazo (Peru), cachilupi (Chile), chévere (Caribbean Islands), chido (Mexico), chilero (Guatemala), chilo (Northwestern Mexico), chiva (Costa Rica), chivo (El Salvador), choro (Chile), dabuten (Spain), fetén (Spain), fino (Venezuela), guay (Spain), lindo (Argentina), machete (Venezuela), mostro (Peru), nota (Venezuela), padre (Mexico), pavo (Venezuela), pura vida (Costa Rica), suave (Mexico), tuanis (Costa Rica), piola

• German: kühl, cool
• Italian: tranquillo, calmo, imperturbabile
• Portuguese: de boa (Brazil)
• Russian: невозмути́мый

cool (uncountable)

1. A moderate or refreshing state of cold; moderate temperature of the air between hot and cold; coolness.

   in the cool of the morning

2. A calm temperament.

   Synonyms: calmness, composure

3. The property of being cool, popular or in fashion.

• French: frais
• Italian: fresco
• Russian: прохла́да

• French: calme, sang-froid
• Italian: posato, calmo
• Russian: хладнокро́вие

From Middle English colen, from Old English cōlian, from Proto-West Germanic *kōlēn, from Proto-Indo-European *gel-.

Cognate with Dutch koelen, German kühlen, Swedish kyla. Also partially from Middle English kelen, from Old English cēlan, from Proto-West Germanic *kōlijan, from Proto-Germanic *kōlijaną, altered to resemble the adjective cool.

cool (cools, present participle cooling; simple past and past participle cooled)

1. (intransitive, literally) To lose heat, to get colder.

   Synonyms: cool down

   Antonyms: warm#Verb, warm up, heat#Verb, heat up

   Hyponym: freeze

   I like to let my tea cool before drinking it so I don't burn my tongue.

2. (transitive, literally) To make cooler, less warm.

   Synonyms: chill#Verb, cool down, refrigerate, ;, deheat

   Antonyms: warm#Verb, warm up, heat#Verb, heat up

   Hyponym: freeze

   • 1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC ↗, Luke 16:24 ↗:

     Send Lazarus, that he may dip the tip of his finger in water, and cool my tongue.

3. (intransitive, figuratively) To become less intense, e.g. less amicable or passionate.

   Relations cooled between the USA and the USSR after 1980.

4. (transitive, figuratively) To make less intense, e.g. less amicable or passionate.
   • c. 1603–1604 (date written), William Shakespeare, “The Tragedie of Othello, the Moore of Venice”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC ↗, [Act I, scene iii]:

     We have reason to cool our raging motions, our carnal stings, our unbitted lusts.

5. (transitive, slang, dated) To kill, murder.
   • 1965, "Sex Jungle" (narrated in Perversion for Profit)

     Maybe he would die. That would mean I had murdered him. I smiled, trying the idea on for size. One of the things that always had cheesed me a little was that I had no kills to my credit. I'd been in plenty of rumbles, but somehow, I'd never cooled anyone. Well maybe now I had my first one. I couldn't feel very proud of skulling an old man, but at least I could say that I'd scored. That was a big kick.

6. (intransitive, AAVE, slang) To relax, hang out.

   Synonyms: bool

• French: refroidir, rafraichir
• Russian: остужа́ть

• German: abkühlen
• Russian: остыва́ть

• Russian: охлажда́ть

1. (programming) Initialism of CLIPS Object-Oriented Language

1. Surname.
   1. Ellipsis of McCool; Surname, anglicized form of McCool.