Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Proto-Celtic
*medu
→
Welsh
meddw
(derived)
→
Welsh
medd
(inherited)
→
Irish
meá
(inherited)
→
Cornish
medh
(inherited)