Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Irish
seinnid
←
Proto-Celtic
*swannati
(inherited)
←
Proto-Indo-European
*swenh₂-
(derived)
→
Irish
seinn
(mention)
→
Scottish Gaelic
seinn
(mention)