kefir

 An effervescent liquor like kumiss, made from fermented milk, used as a food and as a medicine in the northern Caucasus.  [Webster 1913 Suppl.]

 A sour fermented milk drink, used in various regions of Asia, made by addition of Streptococcus or Lactobacillus cultures to cow's or goat's milk; it is considered by some as a form of yoghurt.  [PJC]