Lowers

Lowers is the plural form of the adjective lower, but in English it also appears as a noun in several different contexts to denote parts positioned toward the bottom or beneath a reference point. In firearms terminology, lowers refers to the lower receiver assembly, the serialized part that houses the trigger group and magazine well. The lower is typically paired with an upper receiver to form a complete firearm, and in many jurisdictions possession, manufacture, or sale of lowers is subject to regulation.

In modular systems and engineering, the term lowers can be used more generally to describe the lower portion of a two-part assembly, such as the lower half of a device that can be detached or separated from an upper half. This usage emphasizes position rather than a specific component.

In dentistry and orthodontics, “the lowers” is informal shorthand for the lower dentition—the teeth in the mandible—often contrasted with “the uppers” for the maxillary teeth. Similar informal usage can appear in other domains where a lower section is spoken of in contrast to an upper section.

In broader anatomy or everyday language, lowers can refer to the lower limbs or other structures situated toward the feet or tail end, though this phrasing is more common in casual speech than in formal technical writing. In mathematics, the term lower describes a bound, with “lower bounds” used as standard terminology; the plural noun form “lowers” is not common in formal contexts. See also upper, lower receiver, dentition, and lower bound.