Definition from Wiktionary, the free dictionary
dissociation (plural dissociations)
- The act of dissociating or disuniting; a state of separation; disunion.
- (chemistry) The process by which a compound body breaks up into simpler constituents; said particularly of the action of heat on gaseous or volatile substances.
- the dissociation of the sulphur molecules
- the dissociation of ammonium chloride into hydrochloric acid and ammonia
- (psychology) A defence mechanism where certain thoughts or mental processes are compartmentalised in order to avoid emotional stress to the conscious mind.
- "Project MONARCH could be best described as a form of structured dissociation and occultic integration, carried out in order to compartmentalize the mind into multiple personalities within a systematic framework." —Ron Patton
Related terms 
act of dissociating
chemistry: process of breaking up