- octahedron (n.)
[octahedron 词源字典]
- 1560s, from Greek oktahedron, neuter of oktahedros "eight-sided," from okta- "eight" (see octa-) + hedra "seat" (see sedentary). Related: Octahedral.[octahedron etymology, octahedron origin, 英语词源]
- heptahedron
- "A solid figure with seven plane faces", Late 17th century: from hepta- 'seven' + -hedron, on the pattern of words such as polyhedron.
- pentahedron
- "A solid figure with five plane faces", Late 18th century: from penta- 'five' + -hedron, on the pattern of words such as polyhedron.