Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Galician
custa
←
Galician
custar
(back-formation)
←
Galician
a custa de
(link)
←
Galician
custar
(link)
←
Old Portuguese
custa
(inherited)
→
Galician
custas
(link)