Green’s Dictionary of Slang

1. ‘a person of slovenly attire and unpleasant manners’ (OED).

1653		Rabelais Author’s Prologue (trans.) Gargantua and Pantagruel I 6: So saith a Turlupin or a new start-up grub of my books, but a turd for him.
1667		J. Lacey Sauny the Scot IV i: ’Tis the Old Grub Woodall; What shall we do with him?
1771		Cooke in Foote Maid of Bath Married A2: Reducing the Maid of Bath to the Dilemma of either chusing a Husband out of an old Hunks or Grub, a Debauchee [...] and a mechanical Prig.
1947		S. Lewis Kingsblood Royal (2001) 244: ‘How are you, Captain – Neil?’ the grub hesitated.
1967–8		Baker et al. CUSS 131: Grub An obnoxious person.
1968		J. Alard He who Shoots Last 24: This grub ratted on the kid; in my book he’s dead.
1974		J. McNeil How Does Your Garden Grow Act III: sam: How do I look? mick: Shithouse. Yer a grub.
1986		R.G. Barrett Godson 20: ‘I don’t think the public would like it very much.’ ‘No. But I’m sure those grubs on the newspapers would’.
1990		R.G. Barratt ‘Plague on Puffers’ in What Do You Reckon (1997) [ebook] I just wish smokers would [...] see themselves for the grubs they are.
1994		J. O’Connor Secret World of the Irish Male (1995) 53: You stupid foul-mouthed grub.
2018		G. Gilmore Class Act [ebook] ‘How dare you, you grub’.

2. a dirty, unkempt person, esp. a child, also attrib.

1748		Smollett Roderick Random (1979) 171: Right (said the captain to this miserable grub, who had been an attorney’s boy) you shall have law enough.
1838		T. Hood Comic Annual 131: The Cook’s a hasher nothing more. The Children noisy grubs. A Wife’s a quiz and home’s a bore .
1886		S. Watson Wops the Waif 10/1: It’s lucky that little grub kept her eyes open.
1898		G. du Maurier Martian 390: There were the grubs of Grub Street [...] He did not like to meet them at any Club he belonged to – it was not likely. Clubs have a way of blackballing grubs – especially grubs that are out of the common grubby.
1964		in Current Sl. (1967) I:4 4/2: Grub. n. An untidy person.
1989		R.G. Barrett Boys from Binjiwunyawunya 239: He was one of the greatest grubs Les had ever seen. He wore filthy white jeans, an equally filthy Breaker Morant sweat-shirt [etc.].
1990		Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Grub. A general term of denigration.
2019		C. Hammer Silver [ebook] ‘Another grub journo?’ McGrath spits.

3. (Aus.) tuberculosis.

1950, 1955

‘No. 35’ Argot in G. Simes DAUS (1993).

4. (US teen) one who fails to achieve the popular social norms.

1960		Baltimore Sun (MD) Sun. Mag. 4 Dec. 9/1: [A]lthough she pounded some ground at most of the blasts with Bugsy, the kook always blew the pad with a grub.
2018-20		T. Thorne (ed.) ‘Drill Slang Glossary’ at Forensic Linguistic Databank 🌐 Grub - contemptible person.

5. (US campus) a student kitchen worker.

1966

Current Sl. I:2 3/2: Grub, n. Student kitchen help.