Other forms: sera
A serum is a concentrated liquid treatment for the skin. A face serum, apply the serum, vitamin C serum.
In cosmetics it means thin, light and strongly dosed, and it goes on before a heavier cream. In medicine the word is older and quite different: serum is the clear part of blood left when it clots. The Latin means whey, the watery part of milk.
1nounserumA concentrated liquid skin treatment.
“Apply a few drops of serum to your face before your moisturiser.”
2nounclearThe clear part of blood left when it clots.
“The lab separated the serum from the blood sample to test it for antibodies.”
serum is a liquid.
Latin serum means whey, the watery part left when milk separates. Medicine took it for the clear part of blood.
Latin
serum
English, today
serum
From Latin serum. From Latin serum (“whey”). Cognates include French sérum, Spanish suero, Italian siere, siero, Portuguese soro. a doublet of suero.
Etymology from Wiktionary, CC BY-SA
Practised in Beauty & Cosmetics