Definition of: epigenesis

(ep′ə·jen′ə·sis) noun
1. Biol. The theory that the structure, organization, and development of new organisms, as in embryos, is the result of the successive interactions between male and female cells subsequent to fertilization: opposed to the doctrines of preformation and syngenesis.
2. Geol. An alteration in the character of rocks due to external forces or agents.
3. Med. An accessory or secondary symptom of a disease.
—ep′i·ge·net′ic (-jə·net′ik) adjective