In science and medicine, dermal describes something having to do with skin, like the dermal dryness that makes you itchy in the wintertime.
The adjective dermal is derived from the Greek derma, or "skin." It's mostly used by doctors and scientists to describe skin-related structures, treatments and conditions. In humans for example, the dermal layer is deeper than the outermost, exposed epidermal layer. A synonym for dermal is cutaneous.