adj. & n.
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. equivalence n. equivalency n. equivalently adv.
[ ME f. OF f. LL aequivalere (as EQUI-, valere be worth) ]