The Collaborative International Dictionary of English v.0.48:

M'etis \M['e]`tis"\, n. m. M'etisse \M['e]`tisse"\, n. f.[F.;
   akin to Sp. mestizo. See Mestizo.]
   1. The offspring of a white person and an American Indian.
      [1913 Webster]

   2. The offspring of a white person and a quadroon; an
      octoroon. [Local, U. S.] --Bartlett.
      [1913 Webster]