(tɪˌtɑːtəʊˈhiːdrəl) adj (Chemistry) (of a crystal) having one quarter of the number of faces necessary for the full symmetry of its crystal system[C19: from Greek tetartos one fourth + -hedral]teˌtartoˈhedrallyadvteˌtartoˈhedralism, teˌtartoˈhedrismn