Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Cornish
gevell
←
Breton
gevell
(cognate)
←
Proto-Brythonic
*geβ̃ell
(inherited)
←
Welsh
gefell
(cognate)
←
Latin
gemellus
(derived)
→
Cornish
gevelles
(suffix)