Webster's Revised Unabridged Dictionary · 1913

Equivalence

Equivalence (e*kwiv"ȧ*lens) , noun

[Compare French équivalence, Late Latin aequivalentia.]

1.
The condition of being equivalent or equal; equality of worth, value, signification, or force; as, an equivalence of definitions.
2.
Equal power or force; equivalent amount.
3.
(a) (Chemistry) 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)
(Chemistry) The degree of combining power as determined by relative weight. See Equivalent, n., 2. [Rare]

Equivalence , transitive verb

To be equivalent or equal to; to counterbalance. [Rare] — Sir T. Browne