Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Welsh
cosb
←
Irish
cosc
(cognate)
←
Proto-Indo-European
*sekʷ-
(derived)
→
Welsh
cosbi
(affix)
→
Welsh
cosbol
(affix)
→
Welsh
cic gosb
(compound)
→
Irish
cosc
(cognate)