equivalence

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The state or condition of being equivalent; equality.
2. n. Mathematics An equivalence relation.
3. n. Logic The relationship that holds for two propositions that are either both true or both false, so that the affirmation of one and the denial of the other results in contradiction.

Century Dictionary and Cyclopedia

1. n. The condition of being equivalent; equality in value; correspondence in signification, force, nature, or the like: as, a universal equivalence of weights and measures is extremely desirable; exact equivalence between different words is rare. Also equivalency.
2. To be equivalent to; counterpoise.
3. n. In chem., capability of mutual replacement, in chemical combination, of definite quantities of different substances: thus, there is equivalence between approximately 18.07 parts of aluminium, 40.1 of calcium, 46.1 of sodium, and 55.9 of (ferrous) iron in combining with the same fixed quantity of oxygen.

Wiktionary

1. n. uncountable The condition of being equivalent or essentially equal.
2. n. countable, mathematics An equivalence relation; ≡; ~
3. n. uncountable, logic The relationship between two propositions that are either both true or both false.
4. v. transitive To be equivalent or equal to; to counterbalance.

GNU Webster's 1913

1. n. The condition of being equivalent or equal; equality of worth, value, signification, or force.
2. n. Equal power or force; equivalent amount.
3. n. rare, rare 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.
4. n. rare The degree of combining power as determined by relative weight. See Equivalent, n., 2.
5. v. rare To be equivalent or equal to; to counterbalance.

WordNet 3.0

1. n. a state of being essentially equal or equivalent; equally balanced
2. n. essential equality and interchangeability
3. n. qualities that are comparable