milkyoudaoicibaDictYouDict[milk 词源字典]
milk: [OE] Far back into prehistory, milk traces its ancestry to an Indo-European base *melg-, which denoted ‘wiping’ or ‘stroking’. The way of obtaining milk from animals is to pull one’s hand down their teats, and so *melg- came in due course to be used for ‘milk’. It passed into Germanic as *melk-, which formed the basis of the noun *meluks, and this over the centuries has become German milch, Dutch and Danish melk, Swedish mjölk, and English milk.

The now virtually obsolete adjective milch ‘giving milk’ [OE] (as in milch cow) goes back to a Germanic derivative of *meluks. Another derivative of Indo-European *melgwas the Latin verb mulgēre ‘milk’, which has given English emulsion and promulgate.
=> emulsion, promulgate[milk etymology, milk origin, 英语词源]