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 ith
Proto-Celtic *ɸitu (inherited)
Welsh ŷd (cognate)
Proto-Indo-European *peyt- (root)
Proto-Indo-European *peyt- (derived)
Old Irish ithid (mention)

Irish iothlainn (mention)
Old Irish ithid (mention)