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