Source : Webster's Revised Unabridged Dictionary (1913)

Amitosis \Am`i*to"sis\, n. [NL. See {A-} not, and {Mitosis}.]
   (Biol.)
   Cell division in which there is first a simple cleavage of
   the nucleus without change in its structure (such as the
   formation of chromosomes), followed by the division of the
   cytoplasm; direct cell division; -- opposed to {mitosis}. It
   is not the usual mode of division, and is believed by many to
   occur chiefly in highly specialized cells which are incapable
   of long-continued multiplication, in transitory structures,
   and in those in early stages of degeneration.

Source : WordNet®

amitosis
     n : the direct method of cell division characterized by simple
         division of the nucleus without formation of chromosomes