Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Proto-Mon-Khmer
*rum ~ *ruum ~ *ruəm ~ *ruəp
→
Khmer
រួម
(inherited)
→
Khmer
រោម
(inherited)