Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Welsh
magu
←
Proto-Celtic
*maketi
(inherited)
←
Proto-Indo-European
*meh₂ḱ-
(derived)
←
Middle Welsh
magu
(inherited)
→
Welsh
mag
(back-formation)
→
Welsh
magwr
(affix)