Examples: cartography card archaeology archetype monarchy legal loyal purse personal cinema kinase car carpenter hippopotamus Mesopotamia dative data date
...
Proto-Celtic *kentus

→ Welsh cynt (inherited)
→ Irish céad (inherited)
→ Galician centulo (mention)
→ Middle Irish cét- (inherited)
→ Old Irish cétnae (derived)
→ Old Irish cét- (derived)