Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Church Slavonic
-о-
→
Old Church Slavonic
цѣломѫдриѥ
(affix)
→
Old Church Slavonic
любомѫдриѥ
(affix)