Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Luxembourgish
schwaach
←
Danish
svag
(cognate)
←
German
schwach
(cognate)
←
Proto-West Germanic
*swak
(inherited)
←
Dutch
zwak
(cognate)