köken: Probably from Middle Low German holm (“girt”), from Old Saxon *helma, from Proto-West Germanic *helmō, which pertains to the Germanic root *helmô (compare English helm). Older theories derive it from the plural of dialectal Hulbe (“beam”) with -ben → -m (a rather common development in German). This seems less likely, particularly since Holm was spread by Jahn, who introduced several Low German…