Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Proto-Slavic
[[*sъ(n)|*sъ]] [[*polъ|polъmъ]]
→
Polish
pospołu
(inherited)
→
Ukrainian
посполу
(inherited)