équivalent

äquivalent is a German adjective meaning equivalent, equal in value, function, or meaning. The term stems from Latin aequivalens and entered German through scientific and mathematical usage; the noun form is Äquivalent (singular) or Äquivalente (plural). In everyday language the word is often used for things that can be exchanged on a one-to-one basis without changing outcomes.

In mathematics and logic, äquivalent describes objects or statements that share the same truth value under a given interpretation or relation. For example, two statements are äquivalent if they have the same truth value in every possible situation, and an Äquivalenzrelation partitions a set into äquivalenzklassen (equivalence classes). The concept underpins many formal systems and proofs.

In the natural sciences, particularly chemistry, äquivalent or Äquivalentgewicht refers to the amount of a substance that can react with or supply one mole of reactive units (such as H+ or e−). The historical notion of chemical equivalents guided stoichiometry before modern mole-based accounting became standard; nowadays the concept is often treated in the context of equivalent weight or normality.

In linguistics and translation studies, äquivalent describes expressions in different languages that convey the same meaning, known as translation equivalence. The notion also appears in semantics and philosophy when comparing meanings, where two sentences or concepts may be considered äquivalent under certain interpretations or theories.

See also: Äquivalenz, Äquivalenzrelation, Äquivalentgewicht.