Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Welsh
cachu
←
Proto-Celtic
*kakkā
(inherited)
←
Proto-Indo-European
*kakko-
(inherited)
←
Latin
cacō
(cognate)
→
Welsh
cachadur
(affix)