Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Cornish
edhen
←
Proto-Brythonic
*edn
(inherited)
←
Proto-Celtic
*ɸetnos
(inherited)
←
Middle Cornish
edhyn
(inherited)
←
Proto-Indo-European
*péth₂r̥
(inherited)
←
Old Cornish
hethen
(inherited)
→
Cornish
edhnow
(suffix)