The Collaborative International Dictionary of English v.0.48:

Ounce \Ounce\, n. [F. once; cf. It. lonza, Sp. onza; prob. for
   lonce, taken as l'once, fr. L. lynx, Gr. ?, or an (assumed)
   fem. adj. lyncea, from lynx. Cf. Lynx.] (Zool.)
   A feline quadruped (Felis irbis syn. Felis uncia)
   resembling the leopard in size, and somewhat in color, but it
   has longer and thicker fur, which forms a short mane on the
   back. The ounce is pale yellowish gray, with irregular dark
   spots on the neck and limbs, and dark rings on the body. It
   inhabits the lofty mountain ranges of Asia. Called also
   once.
   [1913 Webster] Ounded