The Collaborative International Dictionary of English v.0.48:

Commix \Com*mix"\, v. t. & i. [imp. & p. p. Commixed; p. pr. &
   vb. n. Commixing.] [Pref. com- + mix: cf. L. commixtus, p.
   p. of commiscere. See Mix.]
   To mix or mingle together; to blend.
   [1913 Webster]

         The commixed impressions of all the colors do stir up
         and beget a sensation of white.          --Sir I.
                                                  Newton.
   [1913 Webster]

         To commix
         With winds that sailors rail at.         --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

commix
    v 1: to bring or combine together or with something else;
         "resourcefully he mingled music and dance" [syn: mix,
         mingle, commix, unify, amalgamate]