Serum

Serum may refer to:

 Biology 
serum (blood), plasma from which the clotting proteins have been removed
Antiserum, blood serum with specific antibodies for passive immunity
Serous fluid, any clear bodily fluid
Any drug derived from an animal's blood or serous fluid
Truth serum, a general term for a drug that is likely to make people tell truth or give information
A word for lotion in the cosmetics market

 People 
Gary Serum (born 1956), retired Major League Baseball pitcher