Source : Webster's Revised Unabridged Dictionary (1913)

Ontogenesis \On`to*gen"e*sis\, Ontogeny \On*tog"e*ny\, n. [See
   {Ontology}, and {Genesis}.] (Biol.)
   The history of the individual development of an organism; the
   history of the evolution of the germ; the development of an
   individual organism, -- in distinction from phylogeny, or
   evolution of the tribe. Called also {henogenesis},
   {henogeny}.

Source : WordNet®

ontogeny
     n : (biology) the process of an individual organism growing
         organically; a purely biological unfolding of events
         involved in an organism changing gradually from a simple
         to a more complex level; "he proposed an indicator of
         osseous development in children" [syn: {growth}, {growing},
          {maturation}, {development}, {ontogenesis}] [ant: {nondevelopment}]