noun, noun which may take the genitive case particle 'no'
pentahedron
A solid figure with five faces. Used in geometry and mathematics.
五面体は五つの面を持つ立体です。
A pentahedron is a solid with five faces.
この結晶は五面体の形をしている。
This crystal has the shape of a pentahedron.
六面体 (hexahedron) has six faces, one more than 五面体.
From 五 (five) + 面 (face) + 体 (body). A straightforward kanji compound for a geometric solid with five faces.