E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Koumiss or Kumiss.
Fermented mares milk used as a beverage by the Tartar tribes of Central Asia. A slightly alcoholic drink of a similar kind is made with great ceremony in Siberia. It consists of slightly sour cows milk, sugar, and yeast. (Russian, kumuisu.)
1
Kumiss is still prepared from mares milk by the Calmucks and Nogais, who, during the process of making it, keep the milk in constant agitation.Rawlinson: Herodotus, vol. iii. book iv. p. 2.
The ceremony of making it is described at full length by Noel, in the Dictionnaire de la Fable, vol. i. 833834.