Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Manx
keyl
←
Proto-Celtic
*koilos
(inherited)
←
Welsh
-
(cognate)
←
Cornish
cul
(cognate)
←
Old Irish
cáel
(inherited)