1.NounThe act of dissociating or disuniting; a state of separation; disunion.
2.NounThe 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; (Can we add an example for this sense?)"
3.NounA defence mechanism where certain thoughts or mental processes are compartmentalised in order to avoid emotional stress to the conscious mind.