Where does “pignon” come from?

pignon (Old French) comes from Latin penna, from Proto-Italic petnā, from Proto-Indo-European péth₂r̥, from Proto-Indo-European peth₂- — to spread out; to fly.

Ancestry of “pignon”, step by step

StepLanguageWordMeaning
1Latinpennawing; feather, especially a flight-feather;...
2Proto-Italicpetnāfeather; wing
3Proto-Indo-Europeanpéth₂r̥wing; feather
4Proto-Indo-Europeanpeth₂-to spread out; to fly
Every word from Proto-Indo-European peth₂- →Every word from Proto-Indo-European péth₂r̥ →Every word from Proto-Italic petnā →