Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Welsh
eithin
←
Proto-Celtic
*ak(s)tīno-
(inherited)
←
Proto-Indo-European
*h₂eḱstis
(inherited)
←
Proto-Indo-European
*h₂eḱ-
(inherited)
→
Irish
aiteann
(cognate)
→
Scottish Gaelic
aiteann
(cognate)