Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Proto-Celtic
*argantom
→
Breton
arc'hant
(inherited)
→
Proto-Brythonic
Ἀργεντοκόξος
(derived)
→
Welsh
arian
(inherited)
→
Irish
airgead
(inherited)
→
Scottish Gaelic
airgead
(inherited)
→
Manx
argid
(inherited)
→
Old Irish
argat
(inherited)