- 1a tough-skinned terrestrial mollusk that typically lacks a shell and secretes a film of mucus for protection. It can be a serious plant pest. See also sea slug.
- Order Stylommatophora, class Gastropoda
- 3an amount of an alcoholic drink, typically liquor, that is gulped or poured:he took a slug of whiskey[ mid 18th century: figuratively from 1sense 4 of the noun) in Oxford Dictionaries (US English)">1sense 4 of the noun]
verb (slugs, slugging, slugged)[with object]
late Middle English (1sense 2 of the noun) in Oxford Dictionaries (US English)">1sense 2 of the noun): probably of Scandinavian origin; compare with Norwegian dialect slugg 'large heavy body'. Sense 1 dates from the early 18th century