Green’s Dictionary of Slang

heavy adv.

1. to a large extent.

[NZ]N.Z. Observer and Free Lance (Auckland) 22 Oct. 18/2: Bill S. is piling it on very heavy with Mary down the way.
[Aus] (ref. to 1810s–50s) Bulletin (Sydney) 23 July 21/4: ‘Tom got home heavily on the olfactory projection’ reads quite imposingly; but what about ‘Sayers pinked him on the smeller,’ or ‘the Slasher napped it heavy on the nozzle’?
[US]W.M. Raine Bucky O’Connor (1910) 78: Course I’ve got the law machinery grinding, too, but I’m not banking on it real heavy.
[US]H. Wiley Wildcat 112: Boy, we eats heavy, ness pa?
[US]R. Chandler ‘Trouble Is My Business’ in Spanish Blood (1946) 195: [He] drinks heavy but hasn’t sicked up on the rugs so far.
[US]W.R. Burnett Asphalt Jungle in Four Novels (1984) 135: He was in hock heavy to a big-mouthed [...] feist.
[US]J. Thompson Savage Night (1991) 112: He couldn’t take it when he was being paid off heavy.
[US]J. Thompson Getaway in Four Novels (1983) 101: He wasn’t carryin’ very heavy when he skipped.
[US]Current Sl. III–IV (Cumulation Issue) 131: He was really trippin’ heavy last night.
[US]E. Torres After Hours 117: I hate gettin’ involved heavy with a chick.
[US]C. White Life and Times of Little Richard 192: I got heavy into narcotics.
[US]E. Richards Cocaine True 79: Paulie was smokin’ the pipe heavy.
[US]Simon & Burns Corner (1998) 155: They’d all been going at the coke heavy.
[UK]J.J. Connolly Layer Cake 55: She’s into the powders heavy.

2. enthusiastically, keenly.

[Aus]Satirist & Sporting Chron. (Sydney) 11 Feb. 2/1: She was doing it heavy in the theatre with one of the B—tts Brothers Clerks, B—yne, while while her husband was using the Cue with another partner in a room hard by.
[NZ]N.Z. Observer (Auckland) 2 Oct. 17/1: I take this early opportunity of wishing Sir Arthur the luck of ‘striking it heavy’.
[UK]Sheffield Wkly Teleg. 21 Mar. 3/4: ‘Come on Swarf-hole, owd lad, owd stick, owd cocklelorum, let’s do it heavy’.
[US](con. 1861) Rock island Argus (IL) 2 June n.p.: Aim low, boys, and give it to ’em heavy!
[US]J. Lait Gangster Girl 94: Boys that age — when they’re trying to bull a broad — go heavy on how brave they are.
[US]Z.N. Hurston Seraph on the Suwanee (1995) 657: He pitched into Dessie hot and heavy.
[US]M. Braly On the Yard (2002) 107: Another time I went in heavy for Alcoholics Anonymous, not that I ever did much drinking.
[US]E. Torres Carlito’s Way 107: These socio broads always go heavy for that shit about the jungle.
[US]E. Folb Runnin’ Down Some Lines xxiii: Heavy into Black Power bag.
[UK] in R. Graef Living Dangerously 89: They all stick together and they’d come down on you really heavy.
[US]J. Ridley Love Is a Racket 122: I used to gamble heavy there.
[US]C. Hiaasen Star Island (2011) 28: ‘Don’t forget to go heavy on the —’ ‘Sunblock. Yeah, Janet, I know’.

3. of money, possessing, or spending, a large amount.

[US]C. Coe Hooch! 206: At least a hundred carriages and not less than a ten-thousand-dollar monument. If we don’t go that heavy we’ll look cheap.
[US]W. Smith Bessie Cotter 168: Horses cost heavy.
[US]J. Thompson ‘The Frightening Frammis’ in Fireworks (1988) 121: We – tied into Lonsdale at a motor-court. Figured he was carrying heavy.
[US]‘Soulful Spider’ ‘Pimp in a Clothing Store’ in Milner & Milner (1972) 287: I’m holding, heavy, freeze, just bring them on down.
[US]J. Stahl Plainclothes Naked (2002) 201: I can’t tell you his name, but I bet he’d pay pretty heavy.

In phrases

run heavy (v.)

to carry a gun.

[UK]L. Theroux Call of the Weird (2006) 106: Others went down to the courthouse to spring Mike Cain out of jail after his traffic infraction, all carrying guns (‘running heavy’ he called it).