ceramide

This term is primarily used in dermatology, biochemistry, and cosmetic science. In a clinical or scientific context, it refers to the structural lipids that maintain the skin's moisture barrier. In the beauty industry, it is frequently marketed as an active ingredient in moisturizers to imply the restoration of the skin's natural protective layer.

Because it refers to a specific chemical molecule, it is treated as a countable noun when discussing different types of ceramides (e.g., ceramide NP, ceramide AP) or as an uncountable mass noun when referring to the substance in general.