a. [ Hemi- + Gr. &unr_; to turn: cf. F. hémitrope. ] Half turned round; half inverted; (Crystallog.) having a twinned structure. [ 1913 Webster ]
n. That which is hemitropal in construction; (Crystallog.) a twin crystal having a hemitropal structure. [ 1913 Webster ]
n. (Crystallog.) Twin composition in crystals. [ 1913 Webster ]