Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Scottish Gaelic
bac
←
Proto-Celtic
*bakkos
(inherited)
←
Old Irish
baccaid
(inherited)
←
Old Irish
bacc
(mention)
→
Scottish Gaelic
baic
(mention)