Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Cornish
skoodh
←
Proto-Brythonic
*skuɨð
(inherited)
←
Proto-Celtic
*skēdos
(inherited)
←
Old Irish
scíath
(cognate)
→
Cornish
diwskodh
(prefix)