Proto-Indo-European *perkʷ-

→ English forest (root)

→ English farm (derived)

→ English firth (root)

→ English firth (mention)

→ English fir (root)

→ English frith (root)

→ English frith (mention)

→ Old English feorm (derived)

→ Old English fyrhþe (root)

→ Old English fyrhþe (mention)

→ Welsh fferm (derived)

→ French ferme (derived)

→ Old French ferme (derived)

→ Irish feirm (derived)

→ Latin firma (derived)

→ Old Norse fýri (derived)

→ Norman fèrme (derived)

→ Polish ferma (derived)

→ Polish piorun (mention)

→ Yiddish פֿאַרם (derived)