Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Breton
aven
←
Proto-Brythonic
*aβon
(inherited)
←
Middle Breton
avon
(inherited)
→
French
aven
(cognate)