Green’s Dictionary of Slang

hard nut n.

[abbr. phr. hard nut to crack]

1. (also hard knut, hard log) a tough person, a dangerous enemy, anything difficult to achieve; thus hardnutted, tough, ruthless.

[NZ]N.Z. Observer (Auckland) 22 Jan. 181/4: The lady evangelist has cracked so many hard nuts that he thinks that even Belinda may be softened.
[US]E. Nye Baled Hay 79: I will ‘pass in my checks’ without a whimper or a cry, And die as I have lived – ‘a hard nut’.
[UK]E.W. Hornung Amateur Cracksman (1992) 63: He was a hard nut, a much older man than myself.
[Ire]G. Fitzmaurice ‘The Disappearance of Mrs. Mulreany’ Weekly Freeman 16 Nov. (1970) 11: The Lord preserve us, he is a hard nut.
[Aus]West Australian (Perth) 25 Aug. 2/6: I knew there were a few hard nuts about, who were watching an opportunity to rob him while drunk.
[US]Ade Knocking the Neighbors 196–7: it was proven that he stuck Pins into his Grandmother and blew up Elderly Gentlemen with Cannon Crackers and set fire to Houses and was a hard Nut in general.
[Aus]Bulletin (Sydney) 6 Aug. 26/1: Three times within a fortnight in three distinct oyster halls I have seen damage done to hard ‘knuts’ by mere waiters; and I take this opportunity of advising gay devils, night owls, toughs and naughty boys generally to be more Broosmithian in their treatment of waiters and barmen than they have found necessary in the past.
[UK]Dundee Courier 18 Dec. 4: Commissioner Cadman [...] was a notorious character and a ‘hard nut’.
[US]Wood & Goddard Dict. Amer. Sl.
[US]A.J. Barr Let Tomorrow Come 63: I trimmed a hard log, and for the same reason.
[UK]D.L. Sayers Nine Tailors (1984) 228: Here’s this Cobbleigh – a hard nut, by all accounts.
[UK]Galton & Simpson ‘The Picnic’ Hancock’s Half-Hour [Radio script] Stone me, this one’s going to be a hard nut to crack.
[UK]F. Norman Guntz 15: Some of them were hard nuts then and still are.
[UK]T. Parker Frying-Pan 40: I can’t think of any others, except perhaps a few of the hard nuts.
[US]S. Longstreet Straw Boss (1979) 384: I saw we had to be as hardnutted as industry.
[UK]J. Sullivan ‘The Longest Night’ Only Fools and Horses [TV script] I’m a right villain I am! A real hard nut!
[UK]I. Welsh Filth 128: She’s a fuckin hard nut awright.
[UK]Camden New Journal (London) Rev. 4 Sept. VII: A typical Cockney hardnut who has a planning councillor in his pay.
[Aus] D. Whish-Wilson ‘In Savage Freedom’ in Crime Factory: Hard Labour [ebook] Warner could obviously see that Danny was no hard nut.

2. an incorrigible person.

[US]Ade More Fables in Sl. (1960) 181: Convinced that they were Children of Belial and pretty hard Nuts in general.
[US]M. Glass Potash and Perlmutter 49: I always thought Abe Potash was a pretty hard nut.
[Aus]T.A.G. Hungerford Riverslake 113: He’s a hard nut.
[UK]A. Payne ‘The Last Video Show’ in Minder [TV script] 53: You’re a right hard nut and I’m well impressed.
[UK]Guardian Guide 18–24 Sept. 5: This heat-packin’ Philadelphia hardnut had two objectives.