Stratum corneum is the outermost layer of the epidermis and serves as a barrier between the body and the outside environment. There are several synonyms that can be used to describe this layer, including the horny layer, the outer skin layer, the corneal layer, and the keratin layer. These terms all refer to the same anatomical structure and can be used interchangeably depending on the context of the discussion. Understanding the significance of the stratum corneum is important in the fields of dermatology and skin care, as it is responsible for protecting the body from external factors such as UV radiation, pollution, and infection.