Relating to the skin or surface of the body.

The thin layer of skin at the base of the fingernails or toenails, which protects the nail matrix.

A protective layer of wax on the surface of plants, preventing water loss and protecting against pathogens.

A polymer found in the cuticle of plants, contributing to water retention and protection against environmental stress.

The skin, particularly the dermis and epidermis layers.

Referring to the skull or head, particularly the part that houses the brain.

The volume of the cranial cavity, often used as a measure of brain size in comparative anatomy.

Any of the twelve pairs of nerves that originate in the brain and primarily serve the head and neck regions.

The bony structure that forms the head, enclosing and protecting the brain.

A form of photosynthesis in certain plants, such as succulents, where carbon fixation occurs at night to reduce water loss in dry environments.