köken: Etymology tree German Kotbor. Esperanto koto Proto-Indo-European *bʰel-der. Proto-Indo-European *bʰlewH-der. Proto-Indo-European *bʰluH-yé-ti? Latin fluōder. Esperanto flui Esperanto -o Esperanto fluo Esperanto kotofluo From koto (“mud”) + fluo (“stream, current”).