Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Portuguese
vao
←
Proto-Indo-European
*wadʰom
(derived)
←
Proto-Italic
*waðom
(derived)
←
Latin
vadum
(derived)
→
Galician
vao
(inherited)
→
Portuguese
vau
(inherited)