Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Irish
gam
←
Proto-Celtic
*gyemos
(inherited)
→
Breton
goañv
(cognate)
→
Welsh
gaeaf
(cognate)
→
Cornish
gwâv
(cognate)
→
Cornish
gwav
(cognate)