Examples: cartography card archaeology archetype monarchy legal loyal purse personal cinema kinase car carpenter hippopotamus Mesopotamia dative data date
...
Irish agus
← Proto-Celtic *onkus-tus (inherited)
← Proto-Celtic *onkus (mention)
← Old Irish ocus (inherited)

→ Irish is (mention)
→ Irish ag (mention)
→ Irish fogas (doublet)
→ Irish aguisín (affix)
→ Irish agusóir (affix)
→ Irish agús (mention)