evolutionary UK /ˌiː.vəˈl(j)uː.ʃən.ɹi/US /ˌiː.vəˈluː.ʃən.ɛɹ.i/ adjective2 •Of or relating to the biological theory of evolution.The evolutionary history of marine mammals includes land-dwelling ancestors. •Having formal similarities to the biological theory of evolution.The basic elements of an evolutionary growth theory are discussed in Section II. — 1974