Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Breton
moc'h
←
Proto-Brythonic
*mox
(inherited)
←
Proto-Celtic
*mokkus
(inherited)
→
Breton
pemoc'h
(compound)