Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Occitan
castel
←
Old French
chastel
(cognate)
←
Latin
castellum
(inherited)
←
Latin
castrum
(mention)
→
Catalan
castell
(inherited)
→
Occitan
castèl
(inherited)
→
Occitan
castèu
(inherited)