# equivalence

[ ih-kwiv-uh-luh ns or for 3, ee-kwuh-vey-luh ns ]

/ ɪˈkwɪv ə ləns or for 3, ˌi kwəˈveɪ ləns /

### noun Also equivalency (for defs 1, 2).

the state or fact of being equivalent; equality in value, force, significance, etc.

an instance of this; an equivalent.

Chemistry. the quality of having equal valence.

Logic, Mathematics.

- Also called material implication. the relation between two propositions such that the second is not false when the first is true.
- Also called material equivalence. the relation between two propositions such that they are either both true or both false.
- the relation between two propositions such that each logically implies the other.

### adjective

(of a logical or mathematical relationship) reflexive, symmetrical, and transitive.

## Nearby words

- equity security,
- equity stock,
- equity weighting,
- equity-linked policy,
- equiv.,
- equivalence class,
- equivalence principle,
- equivalence relation,
- equivalency,
- equivalent

## Origin of equivalence

1535–45; < Middle French < Medieval Latin aequivalentia, equivalent to Latin aequivalent- equivalent + -ia -ia; see -ence

Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

## nonequivalence

/ (ˌnɒnɪˈkwɪvələns) /

### noun

the relationship of being unequal or incomparable

logic

- the relation between two statements only one of which can be true in any circumstances
- a function of two statements that takes the value true only when one but not both of its arguments is true
- a compound statement asserting that just one of its components is true

Abbreviation: exclusive or

## equivalence

### equivalency

/ (ɪˈkwɪvələns) /

### noun

the state of being equivalent or interchangeable

maths logic

- the relationship between two statements, each of which implies the other
- Also called: biconditional the binary truth-function that takes the value true when both component sentences are true or when both are false, corresponding to English if and only if . Symbol: ≡ or ↔, as in –(p ∧ q) ≡ – p ∨ – q

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

## equivalence

1540s, from French équivalence, from Medieval Latin aequivalentia, from aequivalentem (see equivalent). Related: Equivalency (1530s).

Online Etymology Dictionary, © 2010 Douglas Harper