Examples: cartography card archaeology archetype monarchy legal loyal purse personal cinema kinase car carpenter hippopotamus Mesopotamia dative data date
...
Irish eo-
← Irish so- (doublet)
← Ancient Greek εὖ (derived)
← Proto-Indo-European *h₁su- (derived)

→ Irish so- (doublet)
→ Irish eotrófacht (affix)
→ Irish eostatacht (affix)
→ Irish eoigeoiginiúil (affix)