Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Irish
cúig
←
Proto-Celtic
*kʷinkʷe
(inherited)
←
Proto-Indo-European
*pénkʷe
(inherited)
←
Old Irish
cóic
(inherited)
→
Irish
cúigbhliantúil
(affix)
→
Irish
cúigiú
(affix)