Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Welsh
fforch
←
Proto-Brythonic
*forx
(inherited)
←
Welsh
fforc
(doublet)
←
Latin
furca
(derived)
→
Welsh
fforc
(doublet)