洞

1. noun hollow; cavity; hole; cave

うつろ also 虚ろ · 空ろ

1. noun, na-adjective cavity; hollow; void

うろ · うつお · うつほ also 虚 · 空

1. noun hollow; cavity; hole

どう

1. noun, anatomy sinus; cavity; antrum
2. neighborhood (administrative division in North Korea)