Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Irish
cethrar
←
Old Irish
cethair
(affix)
←
Old Irish
-ar
(affix)
→
Irish
ceathrar
(inherited)
→
Scottish Gaelic
ceathrar
(inherited)