Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Welsh
Awst
←
Proto-Brythonic
*aɣust
(inherited)
←
Latin
augustus
(derived)
←
Middle Welsh
Awst
(inherited)
→
Breton
Eost
(cognate)
→
Cornish
Est
(cognate)