In my house, we often ask which words come first–the animals, or the people who share their traits. Like slug/sluggish, sloth/slothful etc.
Well, in the case of slug, the trait definitely came before the critter! It comes from the Scandinavian word slugje, which means “a slow, heavy person.” It’s been in English since the early 15th century. Interestingly, it wasn’t given as a name to a shell-less snail until 1704!
Etymologists aren’t quite sure where the next meaning of slug–a lead bit–came from. Perhaps because of how heavy lead is? No one’s quite sure. But it’s from this secondary meaning that we get the “bullet” meaning. This may have led directly to the meaning of “a hard blow or punch.” The meaning of “swallow” is likely influenced by the Irish slog, which means swallow.


Roseanna M. White is a bestselling, Christy Award winning author who has long claimed that words are the air she breathes. When not writing fiction, she’s homeschooling her two kids, editing, designing book covers, and pretending her house will clean itself. Roseanna is the author of a slew of historical novels that span several continents and thousands of years. Spies and war and mayhem always seem to find their way into her books…to offset her real life, which is blessedly ordinary.