Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Church Slavonic
бо
←
Proto-Slavic
*bo
(inherited)
→
Old Church Slavonic
оубо
(compound)
→
Russian
либо
(compound)