Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Breton
tregont
←
Proto-Celtic
*trīkontes
(inherited)
←
Irish
tríocha
(cognate)
←
Old Breton
tricont
(inherited)
←
Old Irish
trícho
(cognate)
→
Irish
tríocha
(cognate)