Green’s Dictionary of Slang

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

1935		G. & S. Lorimer Heart Specialist 252: It’s an extra-sized, over-stuffed, heavy-duty headache [HDAS].
1977		C. McFadden Serial 29: Naomi, a heavy-duty intellectual, was practically Martha’s guru.
1986		F. Taylor Auf Wiedersehen Pet Two 86: I mean, we’re talkin’ about a heavy-duty villain here.
1993		I. Welsh Trainspotting 64: This is a heavy-duty line-up for a fuckin porter’s job.
2000		Indep. Rev. 13 Jan. 1: He’s a heavy-duty Rasta.

2. (US) tough, unpleasant.

1976		R. Price Blood Brothers 115: Jamaica’s a very heavy-duty place, very poor.
1981		J. Ellroy Brown’s Requiem 171: Heavy-duty shit.
1993		R. Shell Iced 148: I was busy orchestrating a deal with Dalek [...] when the heavy duty shit butchered the fan.
2002		D. Shaw ‘Dead Beard’ at www.asstr.org 🌐 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.
2010		K. Richards Life 229: Yet you know they’re carrying weight, they can bring down some heavy-duty shit.

3. (US) terrific, first-rate.

1954		(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!’.
1979		E. Torres After Hours 10: Carlos Brigante was heavy duty.
1997		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.

1982

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

5. (US drugs) strongly addictive.

a.1982		M. Medved Hospital 36: I never did heavy-duty drugs.
2009		R. Milward Ten Storey Love Song 63: She takes a lot of heavy-duty drugs.

6. (US) fat, overweight.

1995

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