Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Irish
-us
←
Proto-Celtic
*-es[[-tus]]
(inherited)
→
Irish
seanchas
(mention)
→
Old Irish
mórálus
(affix)