[ seer-uhm ]
/ ˈsɪər əm /
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noun, plural se·rums, se·ra [seer-uh]. /ˈsɪər ə/.
the clear, pale-yellow liquid that separates from the clot in the coagulation of blood; blood serum.
any watery animal fluid.
the thin, clear part of the fluid of plants.
milk whey.
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Origin of serum

1655–65; <Latin: whey


se·rum·al, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

How to use serum in a sentence

British Dictionary definitions for serum

/ (ˈsɪərəm) /

noun plural -rums or -ra (-rə)
antitoxin obtained from the blood serum of immunized animals
physiol zoology clear watery fluid, esp that exuded by serous membranes
a less common word for whey

Derived forms of serum

serumal, adjective

Word Origin for serum

C17: from Latin: whey
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for serum

[ sîrəm ]

n. pl. se•rums
A watery fluid, especially one that moistens the surface of serous membranes or that is exuded by such membranes when they become inflamed.
The clear yellowish fluid obtained upon separating whole blood into its solid and liquid components.
Such fluid from the tissues of immunized animals, containing antibodies and used to transfer immunity to another individual.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for serum

[ sîrəm ]

Plural serums sera
See blood serum.
Blood serum extracted from an animal that has immunity to a particular disease. The serum contains antibodies to one or more specific disease antigens, and when injected into humans or other animals, it can transfer immunity to those diseases.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.