Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Irish
áth
←
Proto-Celtic
*yātus
(inherited)
←
Proto-Indo-European
*yeh₂-
(root)
→
Irish
áth
(inherited)
→
Scottish Gaelic
àth
(inherited)
→
Manx
aah
(inherited)