Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Cornish
tus
←
Proto-Brythonic
*tʉd
(inherited)
←
Proto-Celtic
*toutā
(inherited)
←
Proto-Indo-European
*tewtéh₂
(inherited)
→
Cornish
tus efanvos
(affix)