Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Irish
ae
←
Proto-Celtic
*awV-
(inherited)
←
Welsh
afu
(cognate)
←
Irish
aebha
(alter)
←
Irish
aobha
(alter)
←
Middle Irish
áe
(inherited)
←
Old Irish
óa
(inherited)
→
Irish
aelus
(affix)