Disassimilation /(?)/

Dis·as·sim·i·la·tion

Disassimilation

n.
  1. The decomposition of complex substances, within the organism, into simpler ones suitable only for excretion, with evolution of energy, -- a normal nutritional process the reverse of assimilation; downward metabolism; -- now more commonly called catabolism. (Physics)
    The breaking down of already existing chemical compounds into simpler ones, sometimes called disassimilation.