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English definition of “serum”

serum

noun [C or U] uk   /ˈsɪə.rəm/ us    /ˈsɪr.əm/ (plural sera   /ˈsɪə.rə/    /ˈsɪr.ə/ or serums)

serum noun [C or U] (BLOOD)

the thin yellowish liquid part of the blood : cholesterol levels in blood serumThe circulatory system and blood serum taken from an animal's blood and put into a human in order to fight an infection or a poison: an anti-venom serum

serum noun [C or U] (BEAUTY PRODUCT)

a substance in beauty products that is designed to improve your hair or skin and make it less dryBeauty treatments
(Definition of serum from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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