Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Breton
peder
←
Proto-Celtic
*kʷetesres
(inherited)
←
Welsh
pedair
(cognate)
←
Proto-Indo-European
*kʷetwóres
(inherited)