Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Manx
-ey
←
Proto-Celtic
*-tus
(derived)
←
Irish
-adh
(cognate)
←
Old Irish
-ad
(inherited)
→
Manx
fliaghey
(affix)