From Webster's Revised Unabridged Dictionary (1913)

Fell \Fell\, n. [AS. fell; akin to D. vel, OHG. fel, G. fell, Icel. fell (in comp.), Goth fill L. pellis skin.]
A skin or hide of a beast with the wool or hair on.

We are still handling our ewes, and their fells, you know, are greasy. --Shak.