Geom. and Cryst. Pl. -hedra, -hedrons. Also 9 trapezoedron, erron. trapezihedron. [f. trapezo-, used as combining form of TRAPEZIUM, after tetrahedron, etc. Cf. F. trapezoèdre (Littré).] A solid figure whose faces are trapeziums or trapezoids; as the icositetrahedron or deltohedron, with 24 faces, and the trigonal trapezohedron, with 6. Hence Trapezohedral a., pertaining to or of the form of a trapezohedron.
1816–22. Cleaveland, Treat. Min. & Geol. (ed. 2), I. 361. Another form [in Garnet] is a trapezoedron, or a solid presenting twenty four equal and similar, trapezoidal faces.
1828. Webster, Trapezihedron, a solid bounded by twenty-four equal and similar trapeziums. Ibid. (1847), Trapezohedron.
1849. Dana, Geol., xvii. (1850), 628. Garnet in trapezohedral crystals. Ibid. (1868), Min., 189. Quartz…. Various trapezohedral forms…. Many trapezohedrons in other positions.
1895. Story-Maskelyne, Crystallogr., vii. § 257. The trigonal trapezohedron. Ibid., § 273. The trapezohedral tetartohedron. Ibid., § 274. The trapezohedra that occur on quartz belong to two correlative groups.
