köken: From Middle Dutch *kēp, *kip, from Old Dutch *kip (compare Old Dutch kip (“fetter”)), from Proto-West Germanic *kipp- (“to cut, split”), from Proto-Germanic *kipp- (“to split”), from Proto-Indo-European *ǵey- (“to split, divide, geminate, sprout”). Cognate with Middle Low German kēp ("notch, incision"; > German Low German Keep (“score, notch, nick”)), Old English ċipp (“shaving, chip”).
köken: järri- + peippo; the initial component is of onomatopoeic origin. There are many dialectal variants, such as järri, järriäinen, järni, järnipeippo, jäärni.