Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Welsh
saeth
←
Breton
saezh
(cognate)
←
Proto-Brythonic
*saɣeθ
(inherited)
←
Irish
saighead
(cognate)
←
Cornish
seth
(cognate)
←
Latin
sagitta
(derived)
←
Middle Welsh
saeth
(inherited)
→
Welsh
saethu
(suffix)