slug¹ / sləg/ • n. 1. a tough-skinned terrestrial mollusk (order Stylommatophora, class Gastropoda) that typically lacks a shell and secretes a film of mucus for protection. It can be a serious plant pest. See also sea slug. 2. a slow, lazy person; a sluggard. 3. an amount of an alcoholic drink, typically liquor, that is gulped or poured: he took a slug of whiskey. 4. an elongated, typically rounded piece or metal. ∎  a counterfeit coin; a token. ∎  a bullet, esp. one of lead. ∎  a missile for an air gun. ∎  a line of type in Linotype printing. ∎  Printing a metal bar used in spacing.• v. (slugged , slugging ) [tr.] drink (something, typically alcohol) in a large draft; swig.slug² inf. • v. (slugged, slug·ging) [tr.] strike (someone) with a hard blow: he was the one who'd get slugged. ∎  (slug it out) settle a dispute or contest by fighting or competing fiercely: they went outside to slug it out.• n. a hard blow.

slug1 sluggard XV; †slow-sailing vessel XVI; slow-moving shell-less land-snail XVIII. Based on a stem slug-, repr. also by slug vb. be slow or inert (XV) and earlier by, e.g., †sluggy sluggish (XIII); prob. of Scand. orig. (cf. Sw. dial. slogga be sluggish, Norw. dial. slugg large heavy body).
So sluggish (-ISH1), sluggard (-ARD) XIV, slugabed XVI.

slug Mostly terrestrial gastropod mollusc, identified by the lack of shell and uncoiled viscera. It secretes a protective slime, which is also used to aid locomotion. Length: to 20cm (8in). Class Gastropoda; subclass Pulmonata; genera Arion, Limax. See also sea slug

slug2 irregularly shaped bullet XVII; (typogr.) metal bar, line of type XIX. perh. identical with prec.