slug

Slug is a common name for several kinds of slow-moving, soft-bodied mollusks that lack an external shell, or have a greatly reduced shell. Most terrestrial slugs are pulmonate gastropods; sea slugs are marine opisthobranchs. Slugs include many independent evolutionary lineages, so they are not a single taxonomic group. They are characterised by a slime production, squishy bodies, and a broad array of reproductive strategies.

Not all slugs are closely related; several families and genera exist. Land slugs such as Arionidae and Limacidae; sea slugs include nudibranchs and sacoglossans; their external appearances vary widely.

In publishing and journalism, a slug is a short label used to identify a story as it moves through production. It may be a temporary filename, a newsroom identifier, or a metadata tag. Slugs help staff track versions and organize files.

In web development, a slug is a URL-friendly string derived from a page title, used in the path portion of the URL. Slugs are typically lowercase, use hyphens, and avoid spaces or punctuation. They should be stable and readable.

In typography, a slug is a length of lead or metal used as spacing or to separate blocks of type. Slugs were common in hot metal typesetting and continue to be used in some workflows.

In firearms, a shotgun slug is a single, large projectile fired from a shotgun, as opposed to pellets. Slugs are used for hunting larger game and for defense at close range.