Green’s Dictionary of Slang

spot n.2

[-spot sfx]

1. (orig. US) one year’s imprisonment; usu. with a preceding number as -spot sfx (1)

[US]Sun (N.Y.) 20 June 2/2: Off.—Don’t you remember me in ‘quay’ up there? Con.—Oh, were you there? I don’t recollect you—how long were you there? Off.—Six ‘spots.’ Con.—Was you indeed! I was there seven!
[US]Spokane Press (WA) 22 Sept. 7/3: If a thief servs five years in the poentientiary, he tells you he ‘drew a five spot’.
[US]Irwin Amer. Tramp and Und. Sl. 179: SPOT.–A term in prison, more definitely as ‘a one spot,’ one year, etc.
[US]Monteleone Criminal Sl. (rev. edn) 220: spot A sentence of one year in jail.
[NZ]G. Newbold Big Huey 254: spot (n) [...] 2. One year’s imprisonment.

2. a dollar or pound sterling, usu. with a number sfx but not a specific denomination of a note, which is -spot sfx (2)

[Aus] ‘On the Road to Gundagai’ in ‘Banjo’ Paterson Old Bush Songs 24: With a three-spot cheque between us, as wanted knocking down.
[US]R. Lardner ‘Carmen’ in Gullible’s Travels 35: As long as he’s goin’ to welsh on us I hope he lavishes the eight-spot where it’ll do him some good.
[UK]T. Blacker Kill Your Darlings 229: A three spot for petrol. Didn’t that seem just a bit on the large side?

3. (Aus./N.Z.) a ten-pound note.

[Aus]Baker Popular Dict. Aus. Sl.
[Aus]N. Pulliam I Travelled a Lonely Land (1957) 239/2: spot – a ten-pound note.
[NZ]B. Stewart Broken Arse II i: Look, here’s two spots.

4. (US black) a ten-dollar note.

[US]R. Gover One Hundred Dollar Misunderstanding 25: He go an give me a spot.

5. (Aus./N.Z.) £100; latterly A$100 or NZ$100.

[Aus]S.J. Baker in Sun. Herald (Sydney) 8 June 9/3: The underworld has an extensive vocabulary of financial terms. Among those recorded by Detective Doyle are: [...] ‘spot’ or ‘century,’ £100; ‘monkey,’ £500; ‘grand,’ £1,000.
[Aus]Argus (Melbourne) 13 June 4s/3: 4 ponies = 1 spot.
[Aus]Sun. Mail (Adelaide) 25 Sept. 45/5: He gave me a spot — £100 — and told me crime doesn’t pay.
[Aus] ‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxix 4/5: spot: One hundred dollars or pounds.
[Aus]R. Aven-Bray Ridgey-Didge Oz Jack Lang 45: Spot One hundred dollars.
[NZ]McGill Dict. of Kiwi Sl. 106/2: spot $100 bill, formerly £100 bill, popular among poker players; linked with ‘spot’, to gamble.
[Aus]Ozwords Oct. [Internet] A spot is $100 (formerly £100).
[Aus]T. Peacock More You Bet 67: The ‘$50 note’ is sometimes referred to as [...] ‘half-a-Bradman’ (after the great century-making batsman); while ‘$100’ is a ‘spot’ (as was 100 pound).