Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Manx
keead
←
Proto-Celtic
*kantom
(inherited)
←
Irish
céad
(cognate)
←
Proto-Indo-European
*ḱm̥tóm
(inherited)
←
Old Irish
cét
(inherited)