A heptahedron is a seven-sided polyhedron, and there are several synonyms for this geometric shape. One of the most common synonyms is septahedron. The prefix "sept" refers to the number seven, so this word literally means a seven-sided shape. Another synonym is heptagon, which is simply a two-dimensional shape with seven sides. There is also the term seven-sided prism, which is a heptahedron with two identical polygonal bases and seven rectangular faces connecting them. Other less common synonyms include heptacontahedron and septaplex. However, regardless of the word used, a heptahedron will always have a unique and fascinating geometric structure.