[fur-muh-muh
nt] 
| the vault of heaven; sky. |
| fir·ma·ment (fûr'mə-mənt) n. The vault or expanse of the heavens; the sky. [Middle English, from Old French, from Late Latin firmāmentum, from Latin, support, from firmāre, to strengthen; see firm2.] fir'ma·ment'al (-měn'tl) adj. |
Firmament
from the Vulgate firmamentum, which is used as the translation of the Hebrew _raki'a_. This word means simply "expansion." It denotes the space or expanse like an arch appearing immediately above us. They who rendered _raki'a_ by firmamentum regarded it as a solid body. The language of Scripture is not scientific but popular, and hence we read of the sun rising and setting, and also here the use of this particular word. It is plain that it was used to denote solidity as well as expansion. It formed a division between the waters above and the waters below (Gen. 1:7). The _raki'a_ supported the upper reservoir (Ps. 148:4). It was the support also of the heavenly bodies (Gen. 1:14), and is spoken of as having "windows" and "doors" (Gen. 7:11; Isa. 24:18; Mal. 3:10) through which the rain and snow might descend.