serum
n. C / Un. a thin, watery liquid that is part of the blood or found in some plants. In skincare, it is a light liquid you put on your face to help your skin look better.
n. the clear, yellowish fluid that remains from blood plasma after clotting factors have been removed. Also refers to a highly concentrated, lightweight cosmetic preparation designed to deliver active ingredients deep into the skin.
She applies a vitamin C serum every morning.
The doctor explained that the patient's serum levels showed a significant improvement after the new treatment.
While traditional moisturisers focus on hydration through occlusive barriers, a serum typically contains smaller molecules that penetrate the epidermis more effectively to target specific dermatological concerns.
From Latin serum (“whey”). Cognates include French sérum, Spanish suero, Italian siere, siero, Portuguese soro. Doublet of suero.
Uncountable when referring to the biological fluid; countable when referring to specific commercial skincare products or types of medicinal antitoxins.