serum

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The clear yellowish fluid obtained upon separating whole blood into its solid and liquid components after it has been allowed to clot. Also called blood serum.
2. n. Blood serum from the tissues of immunized animals, containing antibodies and used to transfer immunity to another individual.
3. n. Watery fluid from animal tissue, such as that found in edema.
4. n. Whey.

Century Dictionary and Cyclopedia

1. n. The thin part of milk separated from the curd and oil; whey. Also called serum lactis.
2. n. The clear pale-yellow liquid which separates from the clot in coagulation of the blood; blood-serum.
3. n. Any serous liquid, as chyle or lymph.
4. n. The blood-serum of an animal which has been rendered immune against some disease by injections of increasing quantities of the micro-organism of such disease; antitoxin. See serum diagnosis and immunity, 5.
5. n. An antidiphtheritic serum.

Wiktionary

1. n. The clear yellowish fluid obtained upon separating whole blood into its solid and liquid components after it has been allowed to clot. Also called blood serum.
2. n. Blood serum from the tissues of immunized animals, containing antibodies and used to transfer immunity to another individual, called antiserum.
3. n. A watery fluid from animal tissue, especially one that moistens the surface of serous membranes or that is exuded by such membranes when they become inflamed, such as in edema or a blister.
4. n. The watery portion of certain animal fluids, as blood, milk, etc; whey.
5. n. skincare An intensive moisturising product to be applied after cleansing but before a general moisturiser.

GNU Webster's 1913

1. n. The watery portion of certain animal fluids, as blood, milk, etc.
2. n. A thin watery fluid, containing more or less albumin, secreted by the serous membranes of the body, such as the pericardium and peritoneum.

WordNet 3.0

1. n. an amber, watery fluid, rich in proteins, that separates out when blood coagulates