Source : Webster's Revised Unabridged Dictionary (1913)

Karyokinesis \Kar"y*o*ki*ne`sis\, n. [NL., fr. Gr. ? a nut,
   kernel + ? to move.] (Biol.)
   The indirect division of cells in which, prior to division of
   the cell protoplasm, complicated changes take place in the
   nucleus, attended with movement of the nuclear fibrils; --
   opposed to {karyostenosis}. The nucleus becomes enlarged and
   convoluted, and finally the threads are separated into two
   groups which ultimately become disconnected and constitute
   the daughter nuclei. Called also {mitosis}. See {Cell
   development}, under {Cell}.

Source : WordNet®

karyokinesis
     n : organic process consisting of the division of the nucleus of
         a cell during mitosis or meiosis