General English


  • noun an invertebrate animal without a shell. It causes damage to plants by eating leaves or underground parts, especially in wet conditions.


  • A movable ferrite core which is utilized to vary the inductance of a coil. Also called tuning slug.
  • A lump or piece of metal which is to be further processed.
  • A heavy copper ring which is placed on the core of a relay to obtain delayed operation.


  • noun a line of metal type cast in a casting machine in hot metal setting, made in a Linotype or Intertype machine

Origin & History of “slug”

English has at least two, possibly four distinct words slug. The oldest, ‘shell-less mollusc’ (15th c.), 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 (14th c.) and sluggish (14th c.).

Slug ‘bullet’ (17th c.) 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’ (18th c.) may be the same word, but it has also been speculated that it comes from Irish Gaelic slog ‘swallow’.

Slug ‘hit’ (19th c.) and the related slog (19th c.) probably go back ultimately to the prehistoric Germanic base *slakh-, *slag-, *slōg- ‘hit’ (source of English slaughter, slay, etc).