polyhedron
(pɒlɪˈhiːdrən, -ˈhɛdrən)
Also polyedron. Pl. -a (rarely -ons).
[a. Gr. πολύεδρον a polyhedron, prop. neut. of πολύεδρος adj.: see polyhedral.]
Geom. A solid figure contained by many (i.e., usually, more than six) plane faces; a many-sided solid. Hence, a material body having such a form.
| 1570 Billingsley Euclid xii. xvii. 377 A solide of many sides (which is called a Polyhedron). 1690 Leybourn Curs. Math. 289 In the Sphere EDF inscribe a Polyedron. 1727–41 Chambers Cycl. s.v., Gnomonic Polyhedron, is a stone with several faces, whereon are projected various kinds of dials. 1762 H. Walpole Vertue's Anecd. Paint. (1765) I. vii. 181 Holding a pair of compasses, and by his side a Polyedron, composed of twelve pentagons. 1871 Tyndall Fragm. Sc. (1879) I. xii. 368 The little polyhedra become converted into laminæ. |
| fig. 1851 J. Hamilton Royal Preacher xiv. (1854) 180 They are the polyhedrons of the Church, each punctilio of their own forming a several face. |
b. spec. A lens having many facets, multiplying the image of an object; a multiplying-glass.
| 1727–41 Chambers Cycl. s.v., The eye, through a polyhedron, sees the object repeated as many times as there are sides. 1764 Reid Inquiry vi. xii. (1801) 272 Instances wherein the same object may appear double, triple, or quadruple to one eye, without the help of a polyhedron or multiplying glass. |