Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Irish
tost
←
Proto-Celtic
*tustus
(inherited)
←
Old Irish
tóe
(mention)
←
Old Irish
socht
(mention)
→
Irish
tost
(inherited)
→
Scottish Gaelic
tost
(inherited)
→
Scottish Gaelic
tosd
(inherited)