A Dissociation

1. The act of dissociating or disuniting; a state of separation; disunion.
2. (chemistry) The process by which a compound body breaks up into simplerconstituents; said particularly of the action of heat on gaseous or volatilesubstances.
3. (psychology) A defence mechanismwhere certain thoughts or mentalprocesses are compartmentalised in order to avoid emotional stress to the conscious mind.