slugyoudaoicibaDictgodict[slug 词源字典]
slug: English has at least two, possibly four distinct words slug. The oldest, ‘shell-less mollusc’ [15], originally meant ‘slow or lazy person’. It was not applied to the slow-moving animal until the 18th century. It was probably a borrowing from a Scandinavian source (Norwegian has a dialectal slugg ‘large heavy body’). A similar ancestor, such as Swedish dialect slogga ‘be lazy’, may lie behind the now obsolete English verb slug ‘be lazy’, from which were derived sluggard [14] and sluggish [14]. Slug ‘bullet’ [17] is of uncertain origin.

It may have come from slug ‘mollusc’, in allusion to the shape of the animal, but that suggestion depends on the supposition that slug was being used for the mollusc at least a hundred years before our earliest written record of it. Slug ‘swig of drink’ [18] may be the same word, but it has also been speculated that it comes from Irish Gaelic slog ‘swallow’. Slug ‘hit’ [19] and the related slog [19] probably go back ultimately to the prehistoric Germanic base *slakh-, *slag-, *slōg- ‘hit’ (source of English slaughter, slay, etc).

=> slog[slug etymology, slug origin, 英语词源]
slug (n.1)youdaoicibaDictgodict
"shell-less land snail," 1704, originally "lazy person" (early 15c.); related to sluggard.
slug (n.2)youdaoicibaDictgodict
"lead bit," 1620s, perhaps a special use of slug (n.1), perhaps on some supposed resemblance. Meaning "token or counterfeit coin" first recorded 1881; meaning "strong drink" first recorded 1756, perhaps from slang fire a slug "take a drink," though it also may be related to Irish slog "swallow." Journalism sense is from 1925, originally a short guideline for copy editors at the head of a story.
slug (n.3)youdaoicibaDictgodict
"a hard blow," 1830, dialectal, of uncertain origin; perhaps related to slaughter or perhaps a secondary form of slay.
slug (v.)youdaoicibaDictgodict
"deliver a hard blow with the fist," 1862, from slug (n.3). Related: Slugged; slugging. Slugging-match is from 1878.