Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Irish
arbor
←
Proto-Celtic
*arawar
(inherited)
←
Proto-Indo-European
*h₂erh₃-
(derived)
→
Welsh
erw
(cognate)
→
Irish
arbhar
(inherited)
→
Scottish Gaelic
arbhar
(inherited)