Where does “osm” come from?

osm (Czech) comes from Old Czech osm, from Proto-Slavic osmь, from Proto-Balto-Slavic aśmas, from Proto-Indo-European oḱtṓwos, from Proto-Indo-European oḱtṓw, from Proto-Indo-European aḱ- — sharp, pointed; sharp, pointed, edgy; sharp,...

osm (Czech): eight