Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Middle Low German
o
←
Proto-Germanic
*awjō
(inherited)
←
Norwegian
øy
(cognate)
←
Old Norse
ey
(cognate)
←
Swedish
ö
(cognate)