serum

1 of 2

noun

se·​rum ˈsir-əm How to pronounce serum (audio)
plural sera ˈsir-ə How to pronounce serum (audio) 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

serum

2 of 2

adjective

: 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
Noun
After that, the system set me up with three products — a cleanser, spf moisturizer, and night serum/cream. Madison Yauger, Peoplemag, 4 Mar. 2024 Sabrina Elba discusses the inspiration behind her new serum, her biggest beauty inspirations, what’s next for the brand, and more. Essence, 4 Mar. 2024 Find it on Amazon Get Beautiful Lashes with a New Lash Serum Get fuller lashes with this lash serum that has got people talking. Mia Meltzer, Rolling Stone, 23 Feb. 2024 According to the Arizona Department of Health Services, rabies is always fatal once symptoms occur, however, is preventable with emergency services such as the rabies vaccine and anti-rabies serum. Abigail Celaya, The Arizona Republic, 23 Feb. 2024 The kit includes two sizes of the Good Genes treatment serum, in 15 ml. and 30 ml. bottles. Tim Chan, The Hollywood Reporter, 19 Feb. 2024 Travelers looking to pack light will appreciate that the palm-size disc can serve as both a serum and a moisturizer. Eimear Lynch Monica Khemsurov Kurt Soller Gisela Williams Caitie Kelly Elissa Suh, New York Times, 22 Feb. 2024 Working the gua sha around the face also helped to penetrate serum and facial oils into our tester's skin, which instantly boosted her complexion. Sophie Dodd, Peoplemag, 22 Feb. 2024 No Skin care routine: AM and PM: gentle cleanser, eye cream, retinol serum, moisturizer with SPF. Rachel Wilkerson Miller, SELF, 21 Feb. 2024
Adjective
Lizzo completes her skincare process with a serum facial sheet mask from Cicapair. Charmaine Patterson, Peoplemag, 24 Oct. 2022

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'serum.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

Noun

borrowed from Latin, "whey, wheylike fluid," of uncertain origin

Note: Latin serum has been conventionally linked with Greek orós, of identical meaning, and both compared with the Sanskrit verbal base sar-, allegedly meaning " flow" in Vedic texts (hence P. Chantraine in Dictionnaire étymologique de la langue grecque). More recently, however, this interpretation has been rejected, and sar- read as "run off"—hence Vedic Sanskrit ásarat "ran off," prasísarti "lets run, stretches, extends," not akin to sáraḥ "lake, pond" and related words, which describe still water. The Sanskrit etymon has been further compared with Greek hállomai "(I) spring, hop," Latin salīre "to jump" (see sally entry 2). If this is correct the Indo-European base is *sel-, and any connection to serum and orós impossible; these two words are left then without any certain etymology.

Adjective

from attributive use of serum entry 1

First Known Use

Noun

1651, in the meaning defined at sense 1

Adjective

1876, in the meaning defined above

Time Traveler
The first known use of serum was in 1651

Dictionary Entries Near serum

Cite this Entry

“Serum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/serum. Accessed 18 Mar. 2024.

Kids Definition

serum

noun
se·​rum
ˈsir-əm
plural serums or sera
ˈsir-ə

Medical Definition

serum

1 of 2 noun
se·​rum ˈsir-əm How to pronounce serum (audio)
plural sera -ə How to pronounce serum (audio) 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

More from Merriam-Webster on serum

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!