Green’s Dictionary of Slang

stop (what one is doing)!

1681		Otway Soldier’s Fortune IV ii: Hoa up, hoa up! So, avast there, sir!
1731		Caledonian Mercury 12 Jan. 3/1: Avast there, Brothers, let us overhaul this Business.
1748		Smollett Roderick Random (1979) 164: Avast avast! d--m my heart, if you clap your nippers on me, till I know wherefore!
1751		Smollett Peregrine Pickle (1964) 683: And upon this scrap of paper – no, avast – that’s my discharge from the parish for Moll Trundle.
1761		G. Colman Jealous Wife IV i: Avast, avast, my dear!
1800		‘Jolly Jack of Dover’ in Jovial Songster 77: But says I, back avast there, my dear, I’m not so eager.
1827		T. Morton A School For Grown Children IV iii: But, avast! avast!
1837		‘Nights At Sea’ in Bentley’s Misc. May 479: ‘Avast, ould chap!’ says I.
1841		W.J. Neale Paul Periwinkle 352: Avast with your plaguy nonsense, Spanker.
1851		Melville Moby Dick (1907) 77: But avast! [...] here’s a key that’ll fit, I guess.
1873		W.H. Thomes Bushrangers 120: Avast with your blarney [...] I don’t want to hear it.
1884		W.C. Russell Jack’s Courtship I 300: But avast now! We’ve had enough of philosopherising.
1896		Regiment 25 Apr. Navasl Supp. iii/3: Here’s a jolly Jack Tar, come ashore for the day, / [...] / With his ‘Shiver my timbers!’ ‘Avast!’ and ‘Belay!’ / And other strange things which these naval men say.
1923		J. Manchon Le Slang.