六角

1. Origins, structure, and basic meaning

• Structure: 六角 (ろっかく) denotes a hexagonal or six-sided shape.
• Basic usage: 六角の箱 modifies a box, while 軸が六角だ predicates the shape of a pencil barrel.

2. Common pitfalls and similar expressions

• の modifier and nominal predicate
  • Use の before another noun and だ for predication; the shorter form here describes the same six-sided property as 六角形.