Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Old Church Slavonic
тѧжькъ
←
Proto-Slavic
*tęžьkъ
(inherited)
→
Old Church Slavonic
тѧгость
(suffix)
→
Old Church Slavonic
тѧжесть
(suffix)