Green’s Dictionary of Slang

(UK school) to work overly hard.

1799		‘Diary of a Sporting Etonian’ in Sporting Mag. Dec. XV 111/1: Went to Saunter’s room – found him sapping at Greek.
1830		H. Angelo Reminiscenses II 371: This was [...] a tour de jeu – preferring a continental visit to sap-ing (an Eton term) three years at college for a fellowship.
1849		C. Kingsley Yeast (1851) 15: What’s that book on the ground? Sapping and studying still?
1851		Lytton My Novel (1884–5) I Bk I 880: He was sent to school to learn his lessons, and he learns them. You calls that sapping – I call it doing his duty.
1861		T. Hughes Tom Brown at Oxford (1880) 7: I never was much of a hand at sapping.
1887		‘A Plain Woman’ Poor Nellie I 71: He was ‘sapping’ for the new crammer.
1890		H. Fludyer Letters from Cambridge 46: I’ve got it ready and haven’t to go sapping round to get it.
1899		‘Pot’ & ‘Swears’ Scarlet City 249: If you want to do a little ‘sapping’ now and then, Kraps, that’s the tutor’s name, is always on the premises.
1922		(con. 1900s) S. Leslie Oppidan 48: Sapping was unnecessary, so unpleasant even.