[ih-fyoo-zhuh n]


the act of effusing or pouring forth.
something that is effused.
an unrestrained expression, as of feelings: poetic effusions.
  1. the escape of a fluid from its natural vessels into a body cavity.
  2. the fluid that escapes.
Physics. the flow of a gas through a small orifice at such density that the mean distance between the molecules is large compared with the diameter of the orifice.

Origin of effusion

1350–1400; Middle English (< Anglo-French) < Latin effūsiōn- (stem of effūsiō), equivalent to ef- ef- + fūsion- fusion
Related formsnon·ef·fu·sion, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for effusion

Historical Examples of effusion

  • The first sensation of Vaudemont on reading this effusion was delight.

    Night and Morning, Complete

    Edward Bulwer-Lytton

  • The children greeted him with effusion, and when he sat down Tony sat on his knee.

    Jan and Her Job

    L. Allen Harker

  • And Pierre, in the effusion of his triumph, poured out his heart to her.

  • "I don't think you like papa," said I once to her, in an effusion of confidence.

    That Boy Of Norcott's

    Charles James Lever

  • Not dead; but the same as dead: effusion will carry him off some time to-morrow.

    The O'Donoghue

    Charles James Lever

British Dictionary definitions for effusion



an unrestrained outpouring in speech or words
the act or process of being poured out
something that is poured out
the flow of a gas through a small aperture under pressure, esp when the density is such that the mean distance between molecules is large compared to the diameter of the aperture
  1. the escape of blood or other fluid into a body cavity or tissue
  2. the fluid that has escaped
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 effusion

c.1400, "a pouring out," from Middle French effusion (14c.) and directly from Latin effusionem (nominative effusio) "a pouring forth," noun of action from past participle stem of effundere "pour forth, spread abroad," from ex- "out" (see ex-) + fundere "pour" (see found (v.2)). Figuratively, of speech, emotion, etc., from 1650s.

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for effusion




The escape of fluid from the blood vessels or lymphatics into the tissues or a cavity.
The fluid so escaped.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.