Green’s Dictionary of Slang

a blow; often as plump in the..., a blow to the...

1772		Bridges Burlesque Homer (3rd edn) 9: With a plump / He clapt him down upon his rump.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Plump [...] I’ll give you a plump in the bread basket, or the victualling office: I’ll give you a blow in the stomach.
1794		Sporting Mag. Oct. V 5/2: A plump in the jaw, which broke two of his grinders.
1811		Lex. Balatronicum [as cit. 1785].
1819		‘One of the Fancy’ Tom Crib’s Memorial to Congress 18: Clicks in the gob, / And plumps in the daylights.
1821		‘An Amateur’ Real Life in London I 110: Neat milling we had, what with clouts on the nob, / Home hits in the bread-basket, clicks in the gob, / And plumps in the daylights, a prettier treat / Between two Johnny Raws ’tis not easy to meet.
1862		E. de la Bédollière Londres et les Anglais 316/2: plump, coup de poing.