aequivalens

Aequivalens is a Latin adjective and, in some sources, a noun, meaning equal in value, quantity, or effect. It is used to indicate that two things correspond or match in a given respect, such as value, significance, or outcome. In some late Latin contexts the form also functions as a substantive meaning “an equivalent.”

Etymology traces the word to aequus, meaning equal, and valere, meaning to be worth or strong. The combination conveys the sense of having the same value or power as something else, a sense that later influenced the development of terms in the Romance languages and English, such as equivalent and equivalents.

Usage in Latin literature covers several domains. In philosophy and logic, aequivalens may be used to describe two propositions, terms, or concepts that are equivalent in sense or reference. In law, rhetoric, and everyday prose, the term can describe correspondence or sameness of effect, outcome, or value between two items or actions. The word commonly agrees in gender and number with the noun it modifies (e.g., res aequivalens).

In modern scholarship, aequivalens is primarily of historical interest. Its cognates—equivalente in Romance languages and equivalent in English—are standard terms in mathematics, logic, science, and everyday use. The Latin form is usually cited in discussions of Latin vocabulary and philology rather than in contemporary technical writing. See also: equivalence, equivalent, equação/équivalent (Romance languages).