Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Middle Irish
tan
←
Proto-Celtic
*tanā
(inherited)
←
Proto-Indo-European
*tn̥néh₂
(inherited)
←
Proto-Indo-European
*ten-
(mention)
←
Old Irish
tan
(inherited)