Green’s Dictionary of Slang

nick v.3

[ety. unknown; ? link to SE nick of time]

to avoid, to slip away, to leave on the spur of the moment; often as nick away, nick down/down to etc.

[Scot]W. Scott Heart of Mid-Lothian (1883) 219: It’s d---d hard, when three words of your mouth would give the girl the chance to nick Moll Blood, that you make such scrupling about rapping to them.
[Aus]E. Turner Little Larrikin 274: Trying to induce the driver of the motor, for whom he had a friendship, to promise at the end of the journey to ‘nick away and come too’ [OED].
[UK](con. WWI) E. Lynch Somme Mud 86: Nick along and ask the officers to come to me. [Ibid.] 165: I [...] was just about to nick away [...] when the quack returned with a big dish of red-hot stew.
[Aus]X. Herbert Capricornia (1939) 449: The jonns! [...] Quick — nick over to the tank!
[Aus]R.S. Close Love me Sailor 107: Old Joe jabbed his broken stemmed pipe [...] ‘I just nicked in fer a draw . . .’.
[Aus]D. Stivens Jimmy Brockett 135: I nicked away early this night because I remembered that nothing pleased Sadie more than flowers.
[Aus]D. Niland Big Smoke 121: Nick around to 18, Fletcher Street, tomorrow morning.
[Aus]D. Hewett Bobbin Up (1961) 226: Hurry up then luv and I’ll nick over next.
[NZ]B. Crump Hang On a Minute, Mate (1963) 32: We might nick up and see him.
[Aus]R.S. Close With Hooves of Brass 112: Dithering and frigging about instead of nicking into the scrub with her.
[Aus]B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 14: What say you and me nick in the nearest old English inn and sink a few swift ones?
[Aus]W. Dick Bunch of Ratbags 81: Terry, nick back and lay the bikes on the grass.
[NZ]McGill Dict. of Kiwi Sl. 76/1: nick away to leave, usually surreptitiously or quickly. [...] nick over to visit, usually without warning.
[Scot]I. Welsh Filth 126: Gus decides to nick into Crawford’s while I keep shoatie.
[NZ]McGill Reed Dict. of N.Z. Sl. [as cit. 1988].
[Aus]L. Redhead Peepshow [ebook] Hopefully he was nicking to the car for some condoms.
[Aus]S. Maloney Sucked In 106: Red had refrained from nicking off with my last half-dozen cans of beer.
[Aus]me-stepmums-too-fuckin-hot-mate at www.fakku.net 🌐 She nicked off or something?

In phrases

keep (the) nick (v.) (also keep nicko, keep nikko) [i.e. be prepared to run off]

(Irish) to keep a lookout.

[Ire]B. Behan Quare Fellow (1960) Act I: Have a quiet burn there before the screw comes round. We’ll keep nick.
[Ire](con. 1940s) B. Behan Borstal Boy 299: Tell that reception to keep the nick.
[UK]I. & P. Opie Lore and Lang. of Schoolchildren (1977) 399: In Dublin he is either [...] ‘keeping nicko’.
[Ire]B. Quinn Smokey Hollow 101: All they could do was turn up the radio full blast and continue smoking rolled-up brown paper fags, taking turns to keep nikko for their mother.
nick off (v.) (also nick out)

(orig. Aus.) to leave, to depart, to go from one place to another.

[Aus]‘Miles Franklin’ My Brilliant Career 258: Just when the fun commences you have to nick off home and milk.
[Aus]X. Herbert Capricornia (1939) 372: Get off home — go on, I tell you — nick off — both you!
[Aus]G. Casey It’s Harder for Girls 50: If we’re not going to have him any more what about nicking off before he gets here?
[Aus]D. Niland Big Smoke 76: Nick off quick, you worm, before old Birdie gets you.
[UK]H. Livings Nil Carborundum (1963) Act II: McKendrick knows about me nicking off yes’day.
[Aus]B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 87: I just got to nick out the gents for a few jiffs.
[Aus]S. Gore Holy Smoke 9: They just sit around the camp [...] wishin’ to hell he’d nick orf out of it.
[Aus]Lette & Carey Puberty Blues 1: Things like have sex, smoke cigarettes, nick off from school, go to the drive-in, take drugs, and go to the beach.
[UK]T. Lewis GBH 3: ‘I’ll nick off down there and take advantage of your kind offer’.
[Aus]B. Humphries Traveller’s Tool 79: Every time a business colleague nicked off in mid T-bone through the swing door for a quick slash or a technicolour yawn.
[UK]Reeves & Mortimer Vic Reeves Big Night Out n.p.: She hath nicked off, son.
[Aus]B. Scott Banshee and Bullocky 30: Ah, nick off, Martha, an’ give ’im a go.
[UK]Guardian Rev. 31 Mar. 12: Was it that he left his second wife and nicked off to Switzerland with a girl half his age?
[Aus](con. 1945–6) P. Doyle Devil’s Jump (2008) 267: I thought it best [...] that Mavis and me and the little bloke nick off for a while.