Old French chastaigne

→ English chestnut (derived)

→ Middle English chesteyne (derived)

→ Finnish kastanja (derived)

→ French châtaigne (inherited)

→ Middle French chastaigne (inherited)

→ Old French chastaignier (suffix)

→ Irish castán (derived)

→ Scottish Gaelic castan (derived)

→ Manx castan (derived)

→ Gallo châtain (derived)