Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Proto-Celtic
*exs
→
Irish
éar
(derived)
→
Manx
ass
(inherited)
→
Old Irish
a
(inherited)
→
Old Irish
a/Old Irish
(inherited)