epidermis

Outermost layer(s) of cells on an organism's body. In plants and many invertebrates such as insects, it consists of a single layer of cells. In vertebrates, it consists of several layers of cells.

The epidermis of plants and invertebrates often has an outer noncellular cuticle that protects the organism from desiccation.

In vertebrates, such as reptiles, birds, and mammals, the outermost layer of cells is dead, forming a tough, waterproof layer, which is sloughed off continuously or shed periodically.