Whey (noun)

1. The liquid remaining after milk has been curdled and strained.
2. A byproduct of the manufacture of cheese or casein.

Origin:

From old english hwæg, hweg.

Examples:

1. Whey protein is a popular supplement for bodybuilders.
2. Cheese is made by separating the curds and whey.
3. The whey is a good source of protein and can be used in a variety of products.
4. The whey is used to feed pigs and other livestock.
5. He made whey cheese and drank the whey as a refreshing drink.