Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Manx
ceau
←
Gaulish
cateia
(cognate)
←
Irish
caith
(cognate)
←
Scottish Gaelic
caith
(cognate)
←
Old Irish
caithid
(inherited)
→
Manx
yn-cheau
(prefix)
→
Manx
aacheau
(prefix)