Green’s Dictionary of Slang

1. a warning.

1994		P. Blauner Casino Moon 198: ‘You know, there are some people who might be less than pleased about your success in the fight game’ [...] ‘Thanks for the heads-up’.
2003		Simon & Pelecanos ‘Duck and Cover’ Wire ser. 2 ep. 8 [TV script] I just want to give you a heads-up. That last little item we sent out, it’s wrong.
2006		G. Iles Turning Angel 107: I’m calling to give you a heads-up.
2010		(con. 1973) C. Stella Johnny Porno 98: If you should pick something up [...] I’d appreciate a heads-up.
2015		I. Welsh Decent Ride 366: Tez, ah’m giein ye a heads-up here, mate. It’s bad news.
2015		L. McInerney Glorious Heresies 204: ‘[G]iving you a friendly heads-up about Ryan’s advances’.
2021		C. Hammer Opal Country 416: ‘Thanks for the heads-up, Scaley’.

2. information, facts; the distribution or passing of information.

2000		Guardian Guide 13–19 May 52: When someone asks, ‘let me know how your job interview goes’, what they actually say is: ‘gimme the heads up and lemme know how it breaks’.
2011		BBC News Mag. 20 July 🌐 Lets do a ‘heads up on this issue.
2018		G. Disher Kill Shot [ebook] Muecke turned back to the RSC inspector. ‘Sir?’ ‘A heads-up,’ the inspector said.
2017		D. Winslow The Force [ebook] ‘I’m just giving you a heads-up, is all’.
2020		D. Winslow ‘Broken’ in Broken 39: ‘I just wanted to give you a heads-up’.
2020		G. Disher Consolation 98: ‘A heads-up. I got talking to her [...] and got the distinct impression she’s disappointed’.

3. (US black) a greeting, an act of recognition.

1997		Simon & Burns Corner (1998) 270: ‘Ma,’ he calls from the top, giving her a heads-up.
2012		T. Robinson ‘Saint of Gunners’ in Dirty Words [ebook] ‘Jesus, if you're here, give me a heads-up!’.