Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Galician
firmar
←
Latin
firmāre
(inherited)
←
Latin
firmō
(mention)
←
Old Portuguese
firmar
(derived)
→
Galician
firma
(back-formation)