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…
Uncertain. There are many variants from a common root *kama-, like kamala, kamaja, kamaa, including in related languages (Ingrian kama, Karelian kamaja, kamoa, Ludian kamai). Has sometimes been connected with Lithuanian kami̇́enas (“tree trunk”), but this comparison is dubious.