Solid figure with eight plane faces

• Once hard to bend into shape
• Any polyhedron having eight plane faces
• One of five of Plato he’d put in sort of cartoon

WordNet Word definitions in WordNet
n. any polyhedron having eight plane faces [also: octahedra (pl)]

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Octahedron \Oc`ta*he"dron\, n. [Gr.?, fr. ? eight-side; 'okta- (for 'oktw` eight) + ? seat, base, from ? to sit.] (Geom.) A solid bounded by eight faces. The regular octahedron is contained by eight equal equilateral triangles.

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1560s, from Greek oktahedron , neuter of oktahedros "eight-sided," from okta- "eight" (see octa- ) + hedra "seat" (see sedentary ). Related: Octahedral .

Wikipedia Word definitions in Wikipedia
In geometry , an octahedron (plural: octahedra) is a polyhedron with eight faces. A regular octahedron is a Platonic solid composed of eight equilateral triangles , four of which meet at each vertex. A regular octahedron is the dual polyhedron of a cube ...

Wiktionary Word definitions in Wiktionary
n. (context geometry English) a polyhedron with eight faces; the regular octahedron has regular triangles as faces and is one of the Platonic solids.