穹宇

qióngyǔ
  1. (literary) cave (as a place of residence)
  2. (literary) sky; firmament
  3. cave (as a place of residence)
  4. sky; firmament

Wiktionary

Entry Composition

1 穹 qióng
  1. vault
  2. dome
  3. the sky
2 宇 yǔ
  1. room
  2. universe