Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Proto-Celtic
*su-
→
Welsh
hu-
(inherited)
→
Welsh
heini
(mention)
→
Welsh
hy-
(inherited)
→
Irish
so-
(inherited)