firm

\ \ [14] Firm comes ultimately from Latin firmus ‘stable, strong, immovable’. In its adjectival use, the English word’s semantic line of descent from its Latin original is perfectly clear, but the noun presents a very different story.

\ \ From firmus was derived the verb firmāre ‘make firm, fix’, which in post-classical times came to mean ‘confirm’. It passed into Italian as firmare, which was used in the sense ‘confirm by one’s signature’, hence simply ‘sign’. It formed the basis of a noun firma ‘signature’, and by extension the ‘name under which a business is carried on’, and finally the ‘business’ itself.

\ \ English took the noun over with the latter two meanings in the 18th century.

\ \ Other English words that trace their ancestry back to Latin firmus are firmament [13], from Latin firmāmentum (this originally meant simply ‘strengthening, support’, and acquired the sense ‘sky’ in post-classical times as a literal Biblical translation of Greek steréōma ‘heavenly vault’, a derivative of stereós ‘firm’, which in turn was a literal translation of Hebrew rāqī a ‘heavenly vault’, also derived from a word meaning ‘firm’); furl [16], originally a blend formed in Old French from ferm ‘firm’ and lier ‘tie’ (a relative of English liable); and farm, whose semantic history is quite similar to that of the noun firm.

\ \ Cf.⇒ FARM, FIRMAMENT, FURL