Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Proto-Celtic
*trexsnos
→
Scottish Gaelic
treun
(inherited)
→
Old Irish
trén
(inherited)
→
Old Irish
trec'h
(inherited(sga/br))