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

→ Welsh arwain (cognate)
→ Old Irish téit (affix)
→ Old Irish dodíchet (affix)
→ Old Irish dodíat (affix)
→ Old Irish arcoat (affix)