Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Breton
bed
←
Proto-Brythonic
*bɨd
(inherited)
←
Proto-Celtic
*bitus
(inherited)
←
Welsh
byd
(cognate)
←
Cornish
bys
(cognate)