Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Scottish Gaelic
adha
←
Proto-Celtic
*awV-
(inherited)
←
Welsh
afu
(cognate)
←
Middle Irish
áe
(inherited)
←
Old Irish
óa
(inherited)