I. ˈsir-əm noun
( plural serums or se·ra -ə)
Etymology: Latin, whey, wheylike fluid; akin to Greek oros whey
Date: 1665
1. : the watery portion of an animal fluid remaining after coagulation:
a.
(1) : blood serum
(2) : antiserum
b. : whey
c. : a normal or pathological serous fluid (as in a blister)
2. : the watery part of a plant fluid
II. adjective
Date: 1876
: occurring or found in the blood serum
serum cholesterol
serum antibodies