serum Meaning, Definition & Usage

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

WordNet

Se"rum noun
Etymology
L., akin to Gr. , Skr. sara curd.
Definitions
  1. (Physiol.) (a) The watery portion of certain animal fluids, as blood, milk, etc. (b) A thin watery fluid, containing more or less albumin, secreted by the serous membranes of the body, such as the pericardium and peritoneum.

Webster 1913