The following preliminary historical-comparative investigation of the Indo-European terminology pertaining to dairy products leads to the conclusion that while the words for the ‘cow’ and the process of ‘milking’ belong to the basic vocabulary, a common word for the substance ‘milk’ cannot be safely demonstrated. On the other hand, at least Core Indo-European possessed a rich and subtle vocabulary for the processing of milk into curds, butter and cheese. The lack of a widespread designation for ‘animal milk’, which must surely have existed by the time of the proto-language, is rather puzzling. Even though missing evidence is certainly no proof in itself one might hypothesize that the reason why the word for such an important element of a pastoralist society was not faithfully preserved as part of the stable common cultural vocabulary like, e.g., ‘cow’, ‘sheep’ or ‘wool’ was a restricted use of unprocessed milk for human consumption in the oldest period. At least recent archaeobiological observations suggest that lactose tolerance only developed gradually after the disintegration of the Indo-European unity.