Green’s Dictionary of Slang

dig n.4

[abbr. digger n.1 (2)]

1. an Australian or New Zealand soldier.

[Aus](con. WWI) L. Mann Flesh in Armour 14: [T]here were always diggers [...] passing by with ‘Good day, dig’.
[US]N.Y. Herald Trib. 29 June 9/2: During the last war, the soldiers are known as ‘diggers.’ So revered has this title become that today it is a traditional salute. As the American might say, ‘Hiya, fella,’ the Australian says: ‘G’day, dig’.
[US]Baker ‘Influence of Amer. Sl. on Aus.’ in AS XVIII:4 255: Here are a few of the items included: [...] dig, digger, an Australian soldier.
[UK]D. Davin Breathing Spaces 95: ‘Talks just like a dinkum dig,’ Ted said.

2. a general form of address.

[Aus]Examiner (Launceston, Tas.) 31 July 3/7: It’s grand to hear the ‘Good day, Dig!’ The ‘How’s things, mate?’ [...] in Brisbane-street.
[UK](con. WWI) E. Lynch Somme Mud 72: We have forty fine Australian lads in the mud [...] So long, Digs, So long!
[Aus]Sun. Times (Perth) 15 Jan. 3/8: ‘Suppose you could keep one down?’ I said. ‘Too right, dig. We’ve been doing a perish all day’.
[Aus]Mail (Adelaide) 30 May 9/5: ‘Dig’ [is] now used as a vocatrive for either a prsonal friend or stranger.
[Aus]L. Glassop We Were the Rats 70: ‘Dig,’ he said ominously, ‘tonight is going to be one of those nights you’ll never forget.’.
[UK]D. Davin For the Rest of Our Lives 50: How are you, dig?
[Aus]P. White Season at Sarsaparilla in Four Plays (1965) 110: Digger! Old Dig! Thought you’d surprise me, eh?
[Aus]B. Hesling Dinkumization or Depommification 134: Good on yer, dig!
[NZ]McGill Reed Dict. of N.Z. Sl. 61: dig/digger/old dig Friendly greeting, usually male to male. Specifically an Anzac soldier or returned Anzac serviceman, from WWI the Australians preferring ‘digger’, New Zealanders ‘dig’.

In phrases

old dig (n.)

1. (Aus./N.Z.) a veteran soldier.

[UK]Listener (N.Z.) 28 Jan. 20: 1st, 2nd and 3rd Echelon men are naturally known as the ‘Old Digs’ – men who were there almost before the Pyramids [DNZE].
J. Henderson 22 Battalion 5: Turnbull, an old Dig whose pet aversion was long hair.
[NZ]G. Slatter Gun in My Hand 46: An old dig, a genuine old dig. He went overseas as a boy and into the trenches and took all that was coming. [Ibid.] 220: ‘We’re just old digs now, Ron,’ he is saying. ‘Returned men.’.
[NZ]G. Slatter Pagan Game (1969) 67: He never spoke of his other life as an infantryman except to some old dig at the Soldiers’ Club.
[NZ]N. Holmes Best of Homespun 64: Thus old digs could carouse snugly in their clubrooms [DNZE].
L. Barber New Zealand: a short history 158: By 1943 the ‘old digs’ of the Second Division were tired [...] Some refused to return to the war.
[NZ]Eve. Post (Wellington) 13 May 6: There are [...] vital issues that I think all Old Digs will agree on. You cannot do precision ceremonial drill with present day weapons [DNZE].
see sense 2 above.

2. attrib. use of sense 1.

[NZ]G. Slatter Gun in My Hand 144: The grey jersey and the grey flannel shirt as worn by the Kiwi. Walking back from the tailor in Maadi camp with my old dig shirt.
[NZ]E.G. Webber Look No Hands 124: You remember telling me you didn’t want any of your grogged-up Old Dig friends giving her the lowdown on you?’ [DNZE].