Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Cornish
peth
←
Breton
pezh
(cognate)
←
Proto-Brythonic
*peθ
(inherited)
←
Welsh
peth
(cognate)
←
Irish
cuid
(cognate)