Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Proto-Celtic
*kaikos
→
Welsh
coeg
(inherited)
→
Irish
caoch
(inherited)
→
Scottish Gaelic
caoch
(inherited)
→
Old Irish
cáech
(inherited)