English to English

noun (n)

• introduction during embryonic development of characters or structure not present in the earlier evolutionary history of the strain or species (such as the addition of the placenta in mammalian evolution)(noun.process)

  Synonym:
  caenogenesis, cainogenesis, cenogenesis, kenogenesis
  Antonym:
  palingenesis, recapitulation
  

  source: wordnet30