Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Breton
laezh
←
Proto-Brythonic
*llaɨθ
(inherited)
←
Welsh
llaeth
(cognate)
←
Cornish
leth
(cognate)
←
Latin
lac
(derived)