Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Irish
gein
←
Proto-Celtic
*genan
(inherited)
←
Proto-Indo-European
*ǵenh₁-
(derived)
→
Old Irish
Cóemgen
(mention)