plural sera
ˈsir-ə 
or serums
or serums
1
: the watery, clear portion of an animal fluid:
a
: the clear, yellowish fluid that remains from blood plasma after clotting factors (such as fibrinogen and prothrombin) have been removed by clot formation : blood serum compare antiserum, convalescent serum
b
: a normal or pathological serous fluid (as in a blister)
c
: whey
2
: a usually lightweight cosmetic preparation especially for use on the face
specifically
: a typically water-based, often concentrated preparation that lacks lubricating and thickening agents
an antiaging facial serum
3
: the watery part of a plant fluid
Latex. This, the natural product of the rubber tree, is a suspension of rubber droplets in a watery serum concentrated and stabilized in such a way that the dry rubber content is between 60 and 70 per cent.—
C. A. O'Flaherty
see also truth serum
C. A. O'Flaherty
: occurring or found in the blood serum
serum cholesterol
serum antibodies
Examples of serum in a Sentence
Noun
The patient was administered serum.
Recent Examples on the Web
Jessica Ourisman, Forbes, 16 Dec. 2024
Iron tests: These include tests for serum iron (the amount of iron in your blood), ferritin (a protein that stores iron), and total iron-binding capacity (TIBC, which measures how well your blood carries iron).
—Sarah Jividen, Health, 12 Dec. 2024
Charmaine Patterson, Peoplemag, 24 Oct. 2022
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Noun
Cryogenically preserved and banked in a secure lab, Acorn will soon offer bespoke serums from patients’ stem cell secretions for use at future microneedling appointments.
—Jessica Ourisman, Forbes, 16 Dec. 2024
Iron tests: These include tests for serum iron (the amount of iron in your blood), ferritin (a protein that stores iron), and total iron-binding capacity (TIBC, which measures how well your blood carries iron).
—Sarah Jividen, Health, 12 Dec. 2024
Adjective
Lizzo completes her skincare process with a serum facial sheet mask from Cicapair.
—Charmaine Patterson, Peoplemag, 24 Oct. 2022
See all Example Sentences for serum
Dictionary Entries Near serum
Cite this Entry
“Serum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/serum. Accessed 30 Dec. 2024.
Copy CitationMedical Definition
serum
1 of 2 noun
se·rum
ˈsir-əm
plural sera
-ə
or serums
or serums
: the watery portion of an animal fluid remaining after coagulation:
a(1)
: the clear yellowish fluid that remains from blood plasma after fibrinogen, prothrombin, and other clotting factors have been removed by clot formation
called also blood serum
(2)
b
: a normal or pathological serous fluid (as in a blister)
serum
2 of 2 adjective
: occurring or found in the serum of the blood
serum cholesterol
serum glutamic-oxaloacetic transminase
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