Examples: cartography card archaeology archetype monarchy legal loyal purse personal cinema kinase car carpenter hippopotamus Mesopotamia dative data date
...
Old Irish é-
← Proto-Celtic *an- (inherited)
← Proto-Indo-European *n̥- (inherited)

→ Irish éa- (inherited)
→ Irish éagsúil (mention)
→ Irish éigríochta (mention)
→ Old Irish écsamail (affix)
→ Old Irish étrum (affix)
→ Old Irish écóir (affix)