Where does “firmament” come from?

firmament (Middle French) comes from Old French firmament, 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.

Ancestry of “firmament”, step by step

StepLanguageWordMeaning
1Old Frenchfirmamentfirmament
2LatinfirmamentumA strengthening, support, prop, stay; The...
3Latinfirmōto make firm, strengthen, harden, fortify
4LatinFirmusstrong, powerful
5Proto-Italicfermos—
6Proto-Indo-Europeandʰer-mo-sholding
7Proto-Indo-Europeandʰer-to support; to hold

Words derived from “firmament”

Every word from Proto-Indo-European dʰer- →Every word from Proto-Indo-European dʰer-mo-s →Every word from Proto-Italic fermos →