Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Irish
dotluchethar
←
Proto-Celtic
*tlokʷīti
(derived)
←
Old Irish
to-
(affix)
←
Old Irish
ad·tluchedar
(mention)