名詞 firmament:

1. the apparent surface of the imaginary sphere on which celestial bodies appear to be projected
   同義詞：celestial sphere, sphere, empyrean, heavens, vault of heaven, welkin

1. He rose his head and stared at the firmament.
   他抬起頭，凝望著天空。

fir.ma.ment

n.（名詞）
The vault or expanse of the heavens; the sky.
蒼穹；天空

來源：
Middle English
中古英語
from Old French
源自 古法語
from Late Latin firm3mentum
源自 后期拉丁語 firm3mentum
from Latin [support]
源自 拉丁語 [支撐]
from firm3re [to strengthen] * see firm 2
源自 firm3re [加強] *參見 firm2

【引伸】
fir.mament.al