[dih-soh-see-ey-shuh n, -shee-ey-]


an act or instance of dissociating.
the state of being dissociated; disjunction; separation: the dissociation of church and state.
Physical Chemistry.
  1. the reversible resolution or decomposition of a complex substance into simpler constituents caused by variation in physical conditions, as when water gradually decomposes into hydrogen and oxygen under great heat in such a way that when the temperature is lowered the liberated elements recombine.
  2. electrolytic dissociation.
Psychiatry. the splitting off of a group of mental processes from the main body of consciousness, as in amnesia or certain forms of hysteria.

Nearby words

  1. dissociable,
  2. dissocial,
  3. dissociate,
  4. dissociated anesthesia,
  5. dissociated nystagmus,
  6. dissociation sensibility,
  7. dissociative anesthesia,
  8. dissociative disorder,
  9. dissociative reaction,
  10. dissogeny

Origin of dissociation

1605–15; dis-1 + (as)sociation, modeled on Latin dissociātiō separation

Related formsself-dis·so·ci·a·tion, noun

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

Examples from the Web for dissociation

British Dictionary definitions for dissociation



the act of dissociating or the state of being dissociated
  1. a reversible chemical change of the molecules of a single compound into two or more other molecules, atoms, ions, or radicals
  2. any decomposition of the molecules of a single compound into two or more other compounds, atoms, ions, or radicals
separation of molecules or atoms that occurs when a liquid or solid changes to a gas
psychiatry the separation of a group of mental processes or ideas from the rest of the personality, so that they lead an independent existence, as in cases of multiple personality
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 dissociation



1610s, from French dissociation, from Latin dissociationem (nominative dissociatio), noun of action from past participle stem of dissociare (see dissociate).

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for dissociation


[dĭ-sō′sē-āshən, -shē-]


The chemical process by which the action of a solvent or a change in physical condition, as in pressure or temperature, causes a molecule to split into simpler groups of atoms, single atoms, or ions.
The separation of an electrolyte into ions of opposite charge.
Separation of a group of related psychological activities into autonomously functioning units, as in the generation of multiple personalities.
Related formsdis•soci•ate′ v.dis•soci•a′tive adj.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for dissociation



The separation of a substance into two or more simpler substances, or of a molecule into atoms or ions, by the action of heat or a chemical process. Dissociation is usually reversible.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.