Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Breton
avel
←
Proto-Brythonic
*awel
(inherited)
←
Proto-Celtic
*awelā
(inherited)
←
Welsh
awel
(cognate)
←
Old Breton
auel
(inherited)
→
Welsh
awel
(cognate)