Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Cornish
dorn
←
Proto-Celtic
*durnos
(inherited)
←
Welsh
dwrn
(cognate)
←
Irish
dorn
(cognate)
→
Cornish
dornow
(suffix)
→
Cornish
dewdhorn
(prefix)