Where does “koopster” come from?

koopster (Dutch) comes from Dutch kopen, from Middle Dutch côpen, from Old Dutch cōpon, from Proto-West Germanic *kaupōn, from Proto-Germanic kaupōną, from Proto-Germanic kaupô, from Latin caupo, from Proto-Indo-European kaup-.

Ancestry of “koopster”, step by step

StepLanguageWordMeaning
1Dutchkopento buy; plural of koop
2Middle Dutchcôpento buy
3Old Dutchcōponto buy
4Proto-West Germanic*kaupōnto buy
5Proto-Germanickaupōnąto buy; trade
6Proto-Germanickaupôinnkeeper; merchant
7LatincaupoTradesman; Innkeeper, shopkeeper
8Proto-Indo-Europeankaup-—
Every word from Proto-Indo-European kaup- →Every word from Latin caupo →Every word from Proto-Germanic kaupô →