Pronunciation: (i-kwiv'u-luns or, for 3, ē"kwu-vā'luns),[key] —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 calledmaterial implication. the relation between two propositions such that the second is not false when the first is true.
b. Also calledmaterial 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. (of a logical or mathematical relationship) reflexive, symmetrical, and transitive. Also,equivalency(for defs. 1, 2).