[koh-heer-uhns, -her-]
  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 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for coherency

Historical Examples of coherency

  • This search for coherency must not be transferred to the study of real men.

  • There is no consistency which has not once been inconsistent, nor coherency that has not been incoherent.

  • She had even imparted to her, when it came to the issue, something of coherency.

    Adrienne Toner

    Anne Douglas Sedgwick

  • The Customs Union was invented in 1828 to supply the necessary element of coherency.


    Bradley A. Fiske

  • George managed to get through it with a coherency understandable, but no more.

    The Carpet from Bagdad

    Harold MacGrath

British Dictionary definitions for coherency


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 coherency



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

coherency 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.