köken: Inherited from Old Spanish firme, inherited from Vulgar Latin *fīrmis, from Latin firmus, from Proto-Italic *fermos, from Proto-Indo-European *dʰer-mo-s (“holding”), from the root *dʰer- (“to hold”). The preservation of initial /f/ is irregular, but Coromines & Pascual reject the possibility of the word being a borrowing.
aile: a pie firme, de firme, en firme, firmemente, mantenerse firme, sentencia firme, tierra firme
Etymology tree Proto-Indo-European *né Proto-Indo-European *n̥- Proto-Italic *n̥- Latin in- Latin penetrābilis Latin impenetrābilis From in- + penetrābilis.