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

→ Irish mess (inherited(ga/sga))
→ Irish meas (inherited)
→ Irish meas (inherited)
→ Irish tomhais (mention)
→ Scottish Gaelic meas (inherited)
→ Scottish Gaelic tomhais (mention)
→ Old Irish tomus (mention)