Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Breton
erv
←
Proto-Celtic
*arwī
(inherited)
←
Welsh
erw
(cognate)
←
Proto-Indo-European
*h₂erh₃wos
(inherited)
←
Cornish
erow
(cognate)
←
Latin
arvus
(cognate)
←
Old Irish
arbar
(cognate)
→
Welsh
erw
(cognate)