Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Proto-Celtic
*lestrom
→
Breton
lestr
(inherited)
→
Welsh
llestr
(inherited)
→
Irish
leastar
(derived)
→
Old Irish
lestar
(derived)