Green’s Dictionary of Slang

hot air n.

also air hot, hot water

1. (orig. US) nonsense, rubbish, empty chatter.

[[US]‘Mark Twain’ & C. Warner Gilded Age 399: The most airy scheme inflated in the hot air of the capital only reached in magnitude some of his lesser fancies, the by-play of his constructive imagination].
[US]Ade Fables in Sl. (1902) 126: They strolled under the Maples, and he talked what is technically known as Hot Air.
[US]‘O. Henry’ ‘The Fifth Wheel’ in Strictly Business (1915) 72: He fed me on biscuits and hot air, and then kicked me down the front steps.
[UK]A.S.G. Lee letter in No Parachute (1968) 20 May 7: A lot of bally hot air, they’re just trying to put the wind up us new boys.
[UK]E. Wallace Squeaker (1950) 73: Do you think that’s hot air?
[UK]V. Davis Gentlemen of the Broad Arrows 72: Most of us thought that Browne was merely releasing ‘hot air’.
[Aus]D. Stivens Courtship of Uncle Henry 39: There was only hot air in his protests.
[US]Kerouac letter 26 Aug. in Charters I (1995) 117: Is this all a lot of hot water? Not from this point of view: that we will all die some day and it would be one hell of a joke if we all died in darkest ignorance of one another.
[US]H. Simmons Corner Boy 196: They were scared by all that newspaper hot air about teen-age gangs.
[US]J.P. Donleavy Fairy Tales of N.Y. III i: Now why don’t you two be friends and instead of wasting a lot of hot air on each other, use this room the way it’s supposed to be used.
[UK](con. 1940s) J.G. Farrell Singapore Grip 128: Geneva [...] is a city of hot air and hypocrites.
[UK](con. 1950s) D. Nobbs Second From Last in the Sack Race 301: Suddenly his ‘A’ levels were looming [...] Brave talks about exams not being valid tests of a man’s worth were so much hot air.
[UK]Indep. The Information 9–15 Oct. 59: The fuss surrounding Eyes Wide Shut turned out to be hot air.
[US]‘Randy Everhard’ Tattoo of a Naked Lady 57: Hot air’s good for nothin’ but balloons.

2. attrib. use of sense 1.

[Aus] in K. Gilbert Living Black 300: It’s just a perk with nothing to do in between hot-air meetings! Na! Self first, self last, that’s the trouble.

In compounds

hot-air artist (n.) [-artist sfx/merchant n.]

a loquacious person, a person who talks nonsense.

C. Lorenz Tom L. Johnson, Mayor of Cleveland 97: The Senator told the same audiences with all his earnestness, that they had listened to a hot-air artist.
in Some Distinguished Americans 152: He don’t know how to make a livin’ at nuthin’. [...] He’s just a hot-air artist.
[US](con. 1920s) J.T. Farrell Judgement Day in Studs Lonigan (1936) 537: I do know that Ike [...] is one first rate hot air artist.
[US]‘Bill O. Lading’ You Chirped a Chinful!! n.p.: Feather Merchant: Hot air artist.
[US]A. Zugsmith Beat Generation 84: For the sake of melodrama, that hot-air artist would call his own brother a rapist.
M.L. Colley A Summer Story 55: I know, you’re [sic] pop’s the biggest hot air artist in the city, county and state of new York.

In phrases

chew hot air (v.)

to talk nonsense.

[US]J. London Valley of the Moon (2004) 6: Look at your brother, a-runnin’ around to socialist meetin’s, an’ chewin’ hot air.