Green’s Dictionary of Slang

a boxer; a fighter.

c.1786		Grose Classical Dict. of the Vulgar Tongue ms. additions n.p.: Buffer a Boxer/ Irish term.
1788, 1796		Grose Classical Dict. of the Vulgar Tongue (2nd, 3rd edn) n.p.: Buffer. [...] in Ireland it signifies a boxer.
1800		Sporting Mag. June XVI 126/1: The Mercantile Buffers [...] had beaten each other most unmercifully.
1811		Lex. Balatronicum.
1819		‘One of the Fancy’ Tom Crib’s Memorial to Congress 7: The Buffers, both ‘Boys of the Holy Ground’.
1819		T. Moore ‘The Milling Match’ in Farmer Musa Pedestris (1896) 84: Yet, sprightly to the scratch, both Buffers came.
1831		Australian (Sydney) 7 Jan. 3/5: The native lads invariably beat every foreign buffer.
1834		(con. 1737–9) W.H. Ainsworth Rookwood (1857) 258: Bold came each buffer to the scratch, / To make it look a tightish match.
1859		Matsell Vocabulum 125: buffer. A pugilist.
1865		Leaves from Diary of Celebrated Burglar 37/2: Although none of the most valiant of ‘buffers’ at any time, he could not brook this insult.
1873		Sl. Dict.
1890–1904		Farmer & Henley Sl. and Its Analogues.
1895		Crowe Aus. Sl. Dict. 12: Buffer, a pugilist.
1997		Share Slanguage.