Crust; skin; case; coat; cortex; peeling; rind; shell.

1. The external covering of the woody stems, branches, and roots of plants, as distinct and separable from the wood itself. A protective layer of dead corky cells on the outside.
2. Any of several varieties of this substance that can be used in tanning, dyeing, or in medicine.

Verb (used with object)
3. To rub off or scrape the skin of, as in an injury: to bark one's shins.
4. To remove a circle of bark from; girdle.
5. To cover, enclose, or encrust with or as if with bark.
6. To treat with a bark infusion; tan (leather) principally by the tannins in bark.
7. To strip the bark from; peel.
Source: http://www.dictionary.com/browse/bark (freely derived 11-4-2016)