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/i kwiv"euh leuhns/ or, for 3, /ee'kweuh vay"leuhns/, n.1. the state or fact of being equivalent; equality in value, force, significance, etc.2. an instance of this; an equivalent.3. Chem. the quality of having equal valence.4. Logic, Math.a. Also called material implication. the relation between two propositions such that the second is not false when the first is true.b. Also called material equivalence. the relation between two propositions such that they are either both true or both false.c. the relation between two propositions such that each logically implies the other.adj.5. (of a logical or mathematical relationship) reflexive, symmetrical, and transitive.Also, equivalency (for defs. 1, 2).[1535-45; < MF < ML aequivalentia, equiv. to L aequivalent- EQUIVALENT + -ia -IA; see -ENCE]
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▪ logicalso called equivalence of propositionsin logic and mathematics, the formation of a proposition from two others which are linked by the phrase “if, and only if.” The equivalence formed from two propositions p and q also may be defined by the statement “p is a necessary and sufficient condition for q.”▪ prosodyalso called equivalency, plural equivalences or equivalenciesin classical prosody, the principle that one long syllable is equal to two short ones. The principle is used as the basis for substitution in quantitative verse.* * *
Universalium. 2010.