屋上

1. Origins, structure, and basic meaning

• Structure: 屋上 (おくじょう) combines building 屋 and top 上 to denote a rooftop area.
• Basic usage: It can be used for fresh air during lunch or for a small vegetable garden.

2. Common pitfalls and similar expressions

• Usable rooftop space
  • 屋上 often suggests the accessible top level of a building rather than every sloping roof surface.