Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Cornish
gweles
←
Breton
gwelet
(cognate)
←
Proto-Celtic
*weleti
(derived)
←
Welsh
gweld
(cognate)
→
Breton
gwelet
(cognate)
→
Welsh
gweld
(cognate)