Whey \Whey\, n. [AS. hw[ae]g; cf. D. wei, hui, Fries. weye, LG. wey, waje. ] The serum, or watery part, of milk, separated from the more thick or coagulable part, esp. in the process of making cheese.

Note: In this process, the thick part is called curd, and the thin part whey.

Source: Webster's Revised Unabridged Dictionary (1913)