Examples: cartography card archaeology archetype monarchy legal loyal purse personal cinema kinase car carpenter hippopotamus Mesopotamia dative data date
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Old Irish aith-
← Proto-Celtic *ati- (inherited)

→ Irish aiteacht (mention)
→ Manx aa- (inherited)
→ Old Irish adeirrig (affix)
→ Old Irish adeirrig (affix)
→ Old Irish aithirge (affix)
→ Old Irish athchumtach (affix)
→ Old Irish foraithminedar (affix)
→ Old Irish aithesc (affix)
→ Old Irish doaithchuiredar (affix)
→ Old Irish taidchor (affix)
→ Old Irish doaithchren (affix)
→ Old Irish doaithbig (affix)