“In biblical cosmology, the firmament is a vast solid dome, created by God on the second day of creation, which divides the primal waters into upper and lower portions. The word is found in the King James Version, Tyndale, Douay-Rheims, and other early English translations of the Bible.”
– https://en.m.wikipedia.org/wiki/Firmament
Brown-Driver-Briggs Lexicon
Raqia – (???????) – noun masculine Genesis 1:6
– extended surface, (solid) expanse (as if beaten out; compare Job 37:18); absolute ?? Ezekiel 1:22 +, construct ??? Genesis 1:14 +; Greek Version of the LXX ????????, Vulgate firmamentum
Gesenius’ Hebrew-Chaldee Lexicon
“the firmament of heaven, spread out like a hemisphere above the earth, like a splendid and pellucid sapphire (Exodus 24:10, compare Dan. 12:3), to which the stars were supposed to be fixed, and over which the Hebrews believed there was a heavenly ocean (Gen. 1:7; 7:11; Ps.104:3; 148:4; compare, however, Gen. 2:6)”
– https://www.blueletterbible.org/lexicon/h7549/kjv