/di soh'see ay"sheuhn, -shee ay"-/ , n.
1. an act or instance of dissociating.
2. the state of being dissociated; disjunction; separation: the dissociation of church and state.
3. Physical Chem.
a. 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.
b. See electrolytic dissociation .
4. Psychiatry. the splitting off of a group of mental processes from the main body of consciousness, as in amnesia or certain forms of hysteria.
[ 1605-15; DIS- 1 + (AS)SOCIATION, modeled on L dissociatio separation ]