God called the Firmament heaven. And there was evening and there was morning, a second day. Genesis 1:8
Then God said, “Let there be lights in the expanse of the heavens to separate the day from the night, and let them be for signs and for seasons and for days and years. Genesis 1:14
Covering Yourself with light as with a cloak,
Stretching out heaven like a tent curtain. Psalm 104:2
For the choir director. A Psalm of David.
The heavens are telling of the glory of God;
And the Firmament is declaring the work of His hands. Psalm 19:1
In Hebrew, the word is “Raqiya” or “Rakia”. In the bible, the Firmament is a solid expanse.