Green’s Dictionary of Slang

violent and aggressive dancing.

1985		‘Stormtroopers of Death’ [song title] Milano mosh.
1995		Time Out 6–13 Dec. 131/4: [advert] Andy Cairns’ Belfast trio hardened their sound even more for this year’s ‘Infernal Love’ album, a move that delighted both their metal contingent and their indie fans who like a mosh.