Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Middle Welsh
keuen
←
Breton
kein
(cognate)
←
Gaulish
Cebenna
(cognate)
←
Proto-Celtic
*kebno-
(inherited)
←
French
-
(cognate)
←
Cornish
keyn
(cognate)
→
Welsh
cefn
(inherited)
→
Latin
Cebenna
(cognate)