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

Irish an- (inherited)
Irish aníos (mention)
Irish anuas (mention)
Scottish Gaelic a-nuas (mention)
Ancient Greek ἀ- (mention)
Manx neese (mention)
Old Irish anse (affix)
Old Irish dano (affix)
Old Irish amlabar (affix)
Old Irish ancride (affix)
Old Irish andach (affix)