-equivalence-

n. [ Cf. F. équivalence, LL. aequivalentia. ] 1. The condition of being equivalent or equal; equality of worth, value, signification, or force; as, an equivalence of definitions. [ 1913 Webster ]

2. Equal power or force; equivalent amount. [ 1913 Webster ]

3. (Chem.) (a) The quantity of the combining power of an atom, expressed in hydrogen units; the number of hydrogen atoms can combine with, or be exchanged for; valency. See Valence. (b) The degree of combining power as determined by relative weight. See Equivalent, n., 2. [ R. ] [ 1913 Webster ]