Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Irish
immcomairc
←
Proto-Celtic
*ɸarsketi
(derived)
←
Old Irish
imm-
(affix)
←
Old Irish
com-
(affix)