Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Cornish
kenn
←
Breton
skant
(cognate)
←
Irish
scainim
(cognate)
←
Old Irish
ceinn
(cognate)
→
Cornish
kennen
(affix)