Definitions

Definitions are statements that assign meaning to terms or concepts by specifying what they denote and by identifying the essential properties that distinguish the term from other things. They serve to clarify use, reduce ambiguity, and provide a basis for reasoning, communication, and analysis across disciplines.

There are several kinds of definitions. Lexical definitions report how a word is used in a language, reflecting common usage. Stipulative definitions introduce a new term or a new sense of an existing term for a specific purpose. Precising definitions aim to cut down vagueness in a given context, such as legal or academic settings. Theoretical definitions tie a term to a theory, explaining its role within a framework rather than merely describing observable features.

A common definitional form is the genus and differentia: a term is defined by identifying its broad category (genus) and the distinguishing features (differentia). For example, a square can be defined as a plane figure (genus) that is a rectangle with equal sides (differentia). Definitions can also involve necessary and sufficient conditions, though this may be difficult for some terms or contexts.

Good definitions strive for clarity, precision, and non-circularity, avoiding ambiguity and excessive restriction or extension. They should be testable against usage, evidence, and counterexamples, and should align with the purpose of the definition, whether to describe, delimit, or theorize.

Definitions are foundational in dictionaries, science, law, mathematics, and philosophy, where precise interpretation of terms underpins argument, communication, and discovery. They are inherently context-dependent and subject to revision as language and understanding evolve.