Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Icelandic
gagn-
→
English
gain-
(cognate)
→
Icelandic
gagnauga
(affix)
→
Icelandic
gagnkynhneigð
(affix)
→
Icelandic
gagnkynhneigður
(affix)