—adj.
1 (often foll. by to) equal in value, amount, importance, etc.
2 corresponding.
3 (of words) having the same meaning.
4 having the same result.
5 Chem. (of a substance) equal in combining or displacing capacity.
—n.
1 an equivalent thing, amount, word, etc.
2 (in full equivalent weight) Chem. the weight of a substance that can combine with or displace one gram of hydrogen or eight grams of oxygen.
Derivatives:
equivalence n. equivalency n. equivalently adv.
Etymology: ME f. OF f. LL aequivalere (as EQUI-, valere be worth)
Useful english dictionary. 2012.