Green’s Dictionary of Slang

(Can./US/UK teen) a general term of thorough approval.

1985		‘Thommo’ Dict. Aus. Swearing & Sex Sayings 83: MINT — Better than good, great or terrific.
1986		C. Bowles G’DAY 99: If something is [...] very good, it’s magic, top stuf, or mint, but often beaut or ripper.
1989		J. Doyle College Sl. Dict. 🌐 mint [CMU] really cool.
1997–2001		Online Sl. Dict. 🌐 mint adj 1. attractive, usually a male. (‘That guy is mint.’).
2000		Guardian Rev. 3 Nov. 17: Purely Belter means more brilliant than ‘cushdy’ or ‘mint’; it means, as it were, doubleplusgood.
2001		OnLine Dict. of Playground Sl. 🌐 mint, mintox, mont adj. excellent.
2001		OnLine Dict. of Playground Sl. 🌐 real mint n. great, good to look at, fine looking.
2003		McGill Reed Dict. of N.Z. Sl.
2007		R. Milward Apples (2023) 29: Everyone looked mint without the crap baggy [school] shirts and that.