[ dih-fyoo-zhuhn ]
/ dɪˈfyu ʒən /
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act of diffusing; state of being diffused.
prolixity of speech or writing; discursiveness.
  1. Also called migration. an intermingling of molecules, ions, etc., resulting from random thermal agitation, as in the dispersion of a vapor in air.
  2. a reflection or refraction of light or other electromagnetic radiation from an irregular surface or an erratic dispersion through a surface; scattering.
Movies. a soft-focus effect resulting from placing a gelatin or silk plate in front of a studio light or a camera lens, or through the use of diffusion filters.
Meteorology. the spreading of atmospheric constituents or properties by turbulent motion as well as molecular motion of the air.
Anthropology, Sociology.Also called cultural diffusion . the transmission of elements or features of one culture to another.



In effect, this quiz will prove whether or not you have the skills to know the difference between “affect” and “effect.”
Question 1 of 7
The rainy weather could not ________ my elated spirits on my graduation day.

Origin of diffusion

First recorded in 1325–75; Middle English, from Latin diffūsiōn- (stem of diffūsiō ) “a spreading out,” equivalent to diffūs(us) + -iōn- noun suffix; see diffuse, -ion
diffraction, diffusion , reflection, rarefaction, refraction
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

British Dictionary definitions for diffusion

/ (dɪˈfjuːʒən) /


the act or process of diffusing or being diffused; dispersion
  1. the random thermal motion of atoms, molecules, clusters of atoms, etc, in gases, liquids, and some solids
  2. the transfer of atoms or molecules by their random motion from one part of a medium to another
physics the transmission or reflection of electromagnetic radiation, esp light, in which the radiation is scattered in many directions and not directly reflected or refracted; scattering
Also called: diffusivity physics the degree to which the directions of propagation of reverberant sound waves differ from point to point in an enclosure
anthropol the transmission of social institutions, skills, and myths from one culture to another
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

Medical definitions for diffusion

[ dĭ-fyōōzhən ]


The process of diffusing or the condition of being diffused.
The spontaneous intermingling of the particles of two or more substances as a result of random thermal motion.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for diffusion

[ dĭ-fyōōzhən ]

The movement of atoms or molecules from an area of higher concentration to an area of lower concentration. Atoms and small molecules can move across a cell membrane by diffusion. Compare osmosis.
The reflection or refraction of radiation such as light or sound by an irregular surface, tending to scatter it in many directions.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for diffusion


The spreading of atoms or molecules of one substance through those of another, especially into liquids or gases.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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