Equivalence

n.
  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.
    1. 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.
    2. The degree of combining power as determined by relative weight. See Equivalent, n., 2.

v. t.
  1. To be equivalent or equal to; to counterbalance.