Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Middle Welsh
ystlys
←
Proto-Celtic
*stlissus
(inherited)
←
Old Irish
slis
(cognate)
→
Old Irish
slis
(cognate)