Green’s Dictionary of Slang

cool n.2

also coolness
[cool adj.]

1. temper, poise, composure, attitude to life and ability to deal with it.

[UK]Kipling ‘Slaves of the Lamp — Part I’ in Complete Stalky & Co. (1987) 58: ‘Well, that’s pretty average cool,’ said Abanazar.
[UK]Marvel 8 Dec. 28: Not for a moment did the old trapper lose his head, but, with consumate coolness, he continued to fire.
[UK]Magnet 27 Aug. 8: My dear chap, your coolness is too good.
[US]N. Heard Howard Street 156: Pinball, his cool completely gone, said, ‘What the hell are we waitin’ for, man?’.
[US]L. Rosten Dear ‘Herm’ 92: Love is a dangerous disease [...] marked by high fevers, far-out illusions, bad English, and a complete paralysis of cool.
[WI]M. Thelwell Harder They Come 204: Every day dem more desperate too — no have no cool an’ no style neider.
[UK]K. Sampson Powder 8: Identifying with his understated street cool.
[UK]K. Richards Life 68: The height of existentialist cool and pretentiousness.

2. (US teen) a temporary armistice between opposing street gangs.

[US]H. Salisbury Shook-Up Generation (1961) 20: The street and commercial establishments fronting the boundary are no man’s land – safe enough during a ‘cool’.
[US]E. De Roo Big Rumble 29: ‘There’s a cool on. Isn’t there? An armistice?’ ‘How long you figure this cool between the Scratchers and the Spiders is gonna last?’.

3. (orig. US black) sophistication, the prevailing fashion.

[UK]N. Cohn Awopbop. (1970) 108: I’ll even be able to adopt slouching Brando cool.
[US]N. McCall Makes Me Wanna Holler (1995) 27: They set the standard for hip and cool.
[UK]Observer Rev. 9 Jan. 10: Splitting up and dying are the only ways to ensure everlasting coolness.

4. (US campus) a fashionable, drug-taking (or whatever is deemed relevant) young person, as opposed to a straight, conventional person.

[UK]J. Carr Bad (1995) 64: ‘Look here, cool,’ he says to me.
[US]H. Feldman et al. Angel Dust 77: To be ‘cool’ (that is acceptable) among both cools and rowdies, you must be willing to ‘get high’.

5. (US) constr. with the, the epitome of excellence.

[US]The Cut (NY Times Mag.) Mar. 🌐 The Cool (or in Chloe’s words, The Dope, The Awesome, The Lit, The Legit).

In phrases

blow one’s cool (v.)

1. to lose control, to become nervous or angry.

[US]H. Rhodes Chosen Few (1966) 182: He blew his cool, called me some off th’ wall names and finally told me what page he was on.
[US]G.V. Higgins Friends of Eddie Coyle 164: What the fuck’s the matter with you guys down there, you blow your cool permanently.
[US]S. King Running Man in Bachman Books (1995) 573: I’m gettin senile, Bennie, Blowin my cool.
[Scot]I. Welsh Filth 87: Her cool’s blown.
[US]G. Pelecanos Shame the Devil 44: Steve blew his cool, started screaming at the guy over the phone.
[Aus]R.G. Barrett Mystery Bay Blues 121: Hang on a moment, Morgan [...] You’re blowing your cool.

2. to ruin one’s image, to discomfit oneself, to make an exhibition of oneself.

[US]Larner & Tefferteller Addict in the Street (1966) 68: Now if I blew my cool – if I got up and said I was going and they knew what was happening – they couldn’t stop me.
[US]H.E. Roberts Third Ear n.p.: blow one’s cool v. to disconcert.
[UK]Guardian G2 11 Aug. 14: Mack has [...] bolstered his bid for wider acceptance, but blown much of his cool.
[UK]Indep. Rev. 19 May 14: It seems that Mos Def and his crew (of one) have blown their cool.
blow someone’s cool (v.)

to inform upon.

[US]G. Scott-Heron Vulture (1996) 79: A young cat will blow your cool when the Man applies the heat.
hold one’s cool (v.)

(US) to keep calm; to relax.

[US]M. Braly On the Yard (2002) 15: You jus’ hold yore cool [...] They got an assload a time out in that cou’troom — all’s you got to do is back up and get it.
keep one’s cool (v.)

(orig. US) to remain calm, despite circumstances to the contrary.

[US]H. Rhodes Chosen Few (1966) 35: ’Tis merely that thing by which all of us either keep or lose our cool.
[UK]Times 9 Nov. 19: I managed to keep my cool, however, and told him I wouldn’t sign an exclusive contract with anyone.
[US]C. McFadden Serial 32: She kept her cool, since Harvey and his hangups were no longer her problem.
[UK]F. Taylor Auf Wiedersehen Pet Two 171: Keeping his cool, Harry straightened his hat, threw away his cigar and ambled over.
[UK]C. Dexter Remorseful Day (2000) 228: I think he kept his cool.
[Ire]F. Mac Anna Cartoon City 59: Once a woman felt relaxed, then she would get down to it. It was all a matter of keeping his cool.
lose one’s cool (v.)

(orig. US) to lose one’s dignity or self-possession, to lose one’s temper.

[US] ‘Death Row’ in D. Wepman et al. Life (1976) 119: Dig yourself, creep, don’t lose your cool.
[US]H. Rhodes Chosen Few (1966) 180: He’s after your ass and if he can gitcha t’lose your cool, that’s it.
[Can]R. Caron Go-Boy! 56: The Dick lost his cool at something big dumb Rocko had done.
[UK]Beano Special No. 13 n.p.: Oh-oh! Gran’s lost her cool.
[US]T. Willocks Green River Rising 222: Klein was just an asshole losing his cool.
[UK]Observer 6 Feb. 16: Faith, very much losing his cool: ‘Are you going to be serious? Let’s be serious, please’.
[UK]Observer Mag. 1 May. 28/2: Before the last egneerral election he often lost his cool swhen the media focused on the tax affairs of Tory donor Lord Ashcroft.