Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Irish
síon
←
Proto-Celtic
*sīnā
(inherited)
←
Old Irish
sín
(inherited)
→
Irish
síonchlár
(affix)
→
Irish
síondíonach
(affix)