Where does “donderdag” come from?
donderdag (Dutch) comes from Middle Dutch donresdach, from Old Dutch thonaresdag, from Proto-Germanic *Þunras dag, from Latin dies iovis, from Latin diēs, from Proto-Italic djēm, from Proto-Italic *djous, from Proto-Indo-European dyḗws — to be bright; sky, heaven.
donderdag (Dutch): Thursday
Ancestry of “donderdag”, step by step
Words derived from “donderdag”