Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Irish
ochtmad
←
Proto-Celtic
*oxtūmetos
(inherited)
←
Old Irish
ocht
(affix)
←
Old Irish
-mad
(affix)