語源は不明だが、おそらくラテン語のlaxus(ふわふわした、くつろいだ)が語源。
LUSHEY. Drunk. The rolling kiddeys had a spree, and got bloody lushey; the dashing lads went on a party of pleasure, and got very drunk. ["Dictionary of Buckish Slang, University Wit, and Pickpocket Eloquence," London, 1811]