Epigene \Ep"i*gene\, a. [Pref. epi- + Gr. ? to be born, grow.] 1. (Crystallog.) Foreign; unnatural; unusual; -- said of forms of crystals not natural to the substances in which they are found. 2. (Geol.) Formed originating on the surface of the earth; -- opposed to hypogene; as, epigene rocks.