Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Cornish
menydh
→
Breton
menez
(cognate)
→
Welsh
mynydd
(cognate)
→
Scottish Gaelic
monadh
(cognate)
→
Old Irish
Mana
(cognate)
→
Middle Welsh
mynyd
(cognate)