Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Cornish
deg
←
Proto-Brythonic
*deg
(inherited)
←
Proto-Celtic
*dekam
(inherited)
←
Proto-Indo-European
*déḱm̥
(inherited)
→
Cornish
degves
(affix)