[koh-heer-uhns, -her-]
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  1. the act or state of cohering; cohesion.
  2. logical interconnection; overall sense or understandability.
  3. congruity; consistency.
  4. Physics, Optics. (of waves) the state of being coherent.
  5. Linguistics. the property of unity in a written text or a segment of spoken discourse that stems from the links among its underlying ideas and from the logical organization and development of its thematic content.Compare cohesion(def 4).
Also co·her·en·cy.

Origin of coherence

First recorded in 1570–80; coher(ent) + -ence
Related formsnon·co·her·ence, nounnon·co·her·en·cy, noun

Synonyms for coherence

See more synonyms for on Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for coherence


coherency (kəʊˈhɪərənsɪ)

  1. logical or natural connection or consistency
  2. another word for cohesion (def. 1)
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

Word Origin and History for coherence

late 16c., from Middle French cohérence (16c.), from Latin cohaerentia, noun of state from cohaerentem (see coherent). Related: Coherency.

Online Etymology Dictionary, © 2010 Douglas Harper

coherence in Science


[kō-hîrəns, -hĕr-]
  1. A property holding for two or more waves or fields when each individual wave or field is in phase with every other one. Lasers, for example, emit almost perfectly coherent light; all the photons emitted by a laser have the same frequency and are in phase. Since quantum states can be described by a wave equation, coherence can hold for quantum states in general, though only among bosons. Coherence is generally possible in physical systems that may undergo superposition. Maintaining coherence of light is important in fiber optic communications. See also Bose-Einstein condensate.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.