Green’s Dictionary of Slang

heavy-duty adj.

[SE heavy-duty, hard-wearing]

1. (orig. US) intense, serious, committed.

G. & S. Lorimer Heart Specialist 252: It’s an extra-sized, over-stuffed, heavy-duty headache [HDAS].
[US]C. McFadden Serial 29: Naomi, a heavy-duty intellectual, was practically Martha’s guru.
[UK]F. Taylor Auf Wiedersehen Pet Two 86: I mean, we’re talkin’ about a heavy-duty villain here.
[Scot]I. Welsh Trainspotting 64: This is a heavy-duty line-up for a fuckin porter’s job.
[UK]Indep. Rev. 13 Jan. 1: He’s a heavy-duty Rasta.

2. (US) tough, unpleasant.

[US]R. Price Blood Brothers 115: Jamaica’s a very heavy-duty place, very poor.
[US]J. Ellroy Brown’s Requiem 171: Heavy-duty shit.
[US]R. Shell Iced 148: I was busy orchestrating a deal with Dalek [...] when the heavy duty shit butchered the fan.
D. Shaw ‘Dead Beard’ at 🌐 The other thing that everybody knew was that he was dead apple fritter about how Dionne had treated him and wanted to cause her some really heavy duty omar sharif.
[UK]K. Richards Life 229: Yet you know they’re carrying weight, they can bring down some heavy-duty shit.

3. (US) terrific, first-rate.

[US](con. 1920s–30s) J.O. Killens Youngblood (1956) 415: There was a beautiful rhythm in the way she walked. [...] ‘She truly built for speed – ain’t she Youngblood? And heavy duty!’.
[US]E. Torres After Hours 8: Carlos Brigante was heavy duty.
[US]E. Little Another Day in Paradise 134: Not only is this guy a world-class athlete, but a heavy-duty celebrity as well.

4. (US) deeply committed, heavily involved.

[US] W. Safire What’s the Good Word? 5: Eric Heiden is a heavy-duty skater.

5. (US drugs) strongly addictive.

M. Medved Hospital 36: I never did heavy-duty drugs.
[UK]R. Milward Ten Storey Love Song 63: She takes a lot of heavy-duty drugs.

6. (US) fat, overweight.

[UK]Guardian 30 Dec. 90/2: Tim [...] calls Jennifer names to try and shame her into dieting [...] ‘Fat Pig,’ ‘Linebacker,’ ‘Heavy duty’.