Green’s Dictionary of Slang

a sailor; a waterman.

a.1790		H.T. Potter New Dict. Cant (1795) n.p.: lagger a sailor, a person working on the water.
1802		Ordinary of Newgate Account 17 Feb. 🌐 Q. You were told they were stolen from a lagger? – A. Yes. Q. Which slang you understand to mean a sailor? – A. Yes.
1809		G. Andrewes Dict. Sl. and Cant.
1812		Vaux Vocab. of the Flash Lang.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1835		G. Kent Modern Flash Dict. 20: Lagger – a person working on the water.
1847		[A. Harris] (con. 1820s) Settlers & Convicts 94: Old George was always hocussing some poor lagger (sailor).
1849		A. Harris Emigrant Family I 187: He had got the title of ‘the lagger’ (or sailor) among the men .
1859		Matsell Vocabulum 52: lugger A sailor.
1864, 1867, 1870		Hotten Sl. Dict.
1873		Sl. Dict.
1895		C. Crowe Aus. Sl. Dict. 47: Lugger, a sailor.