Where does “costeau” come from?

costeau (Middle French) comes from Old French costel, from Latin costa, from Proto-Indo-European kost-.

Ancestry of “costeau”, step by step

StepLanguageWordMeaning
1Old Frenchcostel—
2Latincostaa rib; a side, a wall
3Proto-Indo-Europeankost-—
Every word from Proto-Indo-European kost- →Every word from Latin costa →Every word from Old French costel →