Where does “achthoekig” come from?

achthoekig (Dutch) comes from Dutch achthoek, from Dutch acht, from Middle Dutch acht, from Old Dutch ahto, from Proto-Germanic ahtō, from Proto-Germanic ahtōu, from Proto-Indo-European oḱtṓw, from Proto-Indo-European aḱ- — sharp, pointed; sharp, pointed, edgy; sharp,...

achthoekig (Dutch): octagonal, having eight corners; shaped like an...