Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Irish
tomus
←
Proto-Celtic
*to-
(derived)
←
Proto-Celtic
*messus
(mention)
←
Proto-Indo-European
*med-
(derived)
→
Irish
tomhais
(mention)
→
Irish
tomhas
(inherited)
→
Scottish Gaelic
tomhais
(mention)
→
Scottish Gaelic
tomhas
(inherited)
→
Old Irish
toimside
(affix)