12th cent. From Vulgar Latin firmis 'id.,' from Latin firmus "strong."
From Proto-Italic *fermo- 'id.' From Proto-Indo-European *dher-mo- "hold." From the root *dher- "to hold" and the noun-forming suffix *-mó- (see -me).
Portuguese firme, Catalan ferm, French ferme, Italian fermo, Romanian ferm, Sardinian fírmu
Sanskrit dhárman- "support," "hold," "law"