pl. sera [L. serum, whey]

1. A pale, watery fluid, esp. the fluid that moistens the surfaces of serous membranes.
2. The watery portion of the blood after coagulation. It is the fluid found when clotted blood is left standing long enough for the clot to shrink.
3. Serum obtained from blood that contains antibodies against a specific microorganism. It is used to provide immediate passive immunity.
SYN: SEE: immune globulin

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