n. [ Gr. &unr_;, &unr_;, a tablet + -oid. ] (Crystallog.) A plane parallel to two of the crystalline axes. [ 1913 Webster ]

n. [ Gr. brachy`s short + E. pinacoid. ] (Crytallog.) A plane of an orthorhombic crystal which is parallel both to the vertical axis and to the shorter lateral (brachydiagonal) axis. [ 1913 Webster ]

n. [ Gr. kli`nein to incline + E. pinacoid. ] (Crystallog.) The plane in crystals of the monoclinic system which is parallel to the vertical and the inclined lateral (clinidiagonal) axes. [ 1913 Webster ]

n. [ Macro- + pinacoid. ] (Crystallog.) One of the two planes of an orthorhombic crystal which are parallel to the vertical and longer lateral (macrodiagonal) axes. [ 1913 Webster ]

n. [ Ortho- + pinacoid. ] (Crystallog.) A name given to the two planes in the monoclinic system which are parallel to the vertical and orthodiagonal axes. [ 1913 Webster ]