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