Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Luxembourgish
domm
←
German
dumm
(cognate)
←
English
dumb
(cognate)
←
Proto-Germanic
*dumbaz
(inherited)
←
Old High German
(inherited)
←
Old High German
tumb
(mention)
←
Dutch
dom
(cognate)
←
Swedish
dum
(cognate)
→
Luxembourgish
Dommheet
(suffix)