Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Cornish
karr
←
Proto-Brythonic
*karr
(inherited)
←
Proto-Celtic
*karros
(inherited)
→
Cornish
kerrik
(affix)
→
Cornish
karrostel
(compound)