The Collaborative International Dictionary of English v.0.48:

Meiosis \Mei*o"sis\ (m[-i]*[=o]"s[i^]s), n. [NL., fr. Gr.
   mei`wsis, fr. meioy^n to make smaller, from mei`wn. See
   Meionite.]
   1. (Rhet.) Diminution; a species of hyperbole, representing a
      thing as being less than it really is; understatement; see
      also litotes.
      [1913 Webster +PJC]

   2. (Cell Biology) The cellular process by which a diploid
      progenitor cell forms haploid gametes, including a
      division of one diploid cell into two cells, each with one
      of the homologous sets of chromosomes.
      [PJC]

WordNet (r) 3.0 (2006):

meiosis
    n 1: (genetics) cell division that produces reproductive cells
         in sexually reproducing organisms; the nucleus divides into
         four nuclei each containing half the chromosome number
         (leading to gametes in animals and spores in plants) [syn:
         meiosis, miosis, reduction division]
    2: understatement for rhetorical effect (especially when
       expressing an affirmative by negating its contrary); "saying
       `I was not a little upset' when you mean `I was very upset'
       is an example of litotes" [syn: litotes, meiosis]