Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Breton
c'hwi
←
Proto-Brythonic
*hwi
(inherited)
←
Proto-Celtic
*swīs
(inherited)
←
Proto-Indo-European
*wos
(inherited)
←
Old Breton
hui
(inherited)