Firmament
FIRMAMENT (Heb. raq̂ia‘). The expanse of sky surrounding the earth, made by God on the second day of creation to “separate water from water” (Gen.1.6). The Hebrews thought of the firmament as the apparent void above in which the clouds float and the lights of heaven are set by God. The Hebrew word suggests something stretched or spread out like a curtain (Isa.40.22). It corresponds to the “empty space” of Job.26.7. Our English word “firmament” does not correctly suggest the real meaning of the Hebrew word. NIV translates it as “expanse.”
International Standard Bible Encyclopedia (1915)
fur’-ma-ment.
See Astronomy. III, 3.