Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Irish
eachtra
←
Proto-Celtic
*extro-
(derived)
←
Welsh
eithr
(cognate)
←
Latin
exter
(cognate)
←
Old Irish
echtra
(inherited)
←
Old Irish
echtar
(mention)
→
Irish
fo-eachtra
(affix)
→
Irish
eachtrach
(affix)
→
Scottish Gaelic
eachdraidh
(cognate)
→
Scottish Gaelic
eachtradh
(cognate)