different between octagon vs octahedron

English

Etymology

From Latin octag?non, oct?g?non (“octagon”), and from its etymon Ancient Greek ????????? (oktág?non, “octagon”), probably from Koine Greek ????????? (oktág?nos, “having eight corners”) + -?? (-on, suffix forming nouns). ????????? is derived from ????- (okta-, prefix meaning ‘eight’) (from ???? (okt?, “eight”), ultimately from Proto-Indo-European *o?t?w (“eight”)) + ????? (g?nía, “angle; corner”) (probably ultimately from Proto-Indo-European *?ónu (“knee”)); analysable as octa- +? -gon. The English word is cognate with Middle French octogone (modern French octogone), Italian octagono (obsolete), ottagono, Spanish octágono, octógono.

Sense 2 (“arena for mixed martial arts”) refers to its shape.

Pronunciation

• (Received Pronunciation) enPR: ?k't?g?n, IPA^(key): /??kt??(?)n/
• (General American) enPR: ?k't?g?n, IPA^(key): /??kt????n/
• Hyphenation: oc?ta?gon

Noun

octagon (plural octagons)

1. (geometry, also attributively) A polygon with eight sides and eight angles.
2. (martial arts) Often in the form Octagon: the arena for mixed martial arts.

Derived terms

• octagonal
• octagonally

Translations

References

Further reading

• octagon on Wikipedia.Wikipedia
• The Octagon, Dunedin on Wikipedia.Wikipedia

English

Etymology

From Ancient Greek ???? (okt?, “eight”) + ???? (hédra, “seat”).

Noun

octahedron (plural octahedra or octahedrons)

1. (geometry) a polyhedron with eight faces; the regular octahedron has regular triangles as faces and is one of the Platonic solids.

Related terms

• octahedral

Translations