Where does “firmament” come from?
firmament (Occitan) comes from Latin firmamentum, from Latin firmō, from Latin Firmus, from Proto-Italic fermos, from Proto-Indo-European dʰer-mo-s, from Proto-Indo-European dʰer- — to support; to hold.
firmament (Occitan): firmament, heavens
Ancestry of “firmament”, step by step