The Editors of Encyclopaedia Britannica offered the following definition of "milk":

“liquid secreted by the mammary glands of female mammals to nourish their young for a period beginning immediately after birth. The milk of domesticated animals is also an important food source for humans, either as a fresh fluid or processed into a number of dairy products such as butter and cheese.”

-

Editors of Encyclopaedia Britannica, “Milk,” britannica.com, May 1, 2022