Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Breton
yar
←
Proto-Celtic
*yarā
(inherited)
←
Welsh
iâr
(cognate)
→
Breton
douryar
(compound)
→
Welsh
iâr
(cognate)