Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Breton
vi
←
Proto-Celtic
*āuyom
(inherited)
←
Welsh
wy
(cognate)
←
Proto-Indo-European
*h₂ōwyóm
(inherited)
←
Cornish
oy
(cognate)
→
Cornish
oy
(cognate)