Source : Webster's Revised Unabridged Dictionary (1913)

Pigskin \Pig"skin`\, n.
   A football; -- so called because the covering is often made
   of pigskin. [Colloq.]

Pigskin \Pig"skin`\, n.
   The skin of a pig, -- used chiefly for making saddles; hence,
   a colloquial or slang term for a saddle.

Source : WordNet®

pigskin
     n : leather from the skin of swine