The Collaborative International Dictionary of English v.0.48:

Mix \Mix\ (m[i^]ks), v. t. [imp. & p. p. Mixed (m[i^]kst)
   (less properly Mixt); p. pr. & vb. n. Mixing.] [AS.
   miscan; akin to OHG. misken, G. mischen, Russ. mieshate, W.
   mysgu, Gael. measg, L. miscere, mixtum, Gr. mi`sgein,
   migny`nai, Skr. mi[,c]ra mixed. The English word has been
   influenced by L. miscere, mixtum (cf. Mixture), and even
   the AS. miscan may have been borrowed fr. L. miscere. Cf.
   Admix, Mash to bruise, Meddle.]
   1. To cause a promiscuous interpenetration of the parts of,
      as of two or more substances with each other, or of one
      substance with others; to unite or blend into one mass or
      compound, as by stirring together; to mingle; to blend;
      as, to mix flour and salt; to mix wines.
      [1913 Webster]

            Fair persuasions mixed with sugared words. --Shak.
      [1913 Webster]

   2. To unite with in company; to join; to associate.
      [1913 Webster]

            Ephraim, he hath mixed himself among the people.
                                                  --Hos. vii. 8.
      [1913 Webster]

   3. To form by mingling; to produce by the stirring together
      of ingredients; to compound of different parts.
      [1913 Webster]

            Hast thou no poison mixed?            --Shak.
      [1913 Webster]

            I have chosen an argument mixed of religious and
            civil considerations.                 --Bacon.
      [1913 Webster]

   4. To combine (two or more activities) within a specified or
      implied time frame; as, to mix studying and partying while
      at college.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Mixed \Mixed\, a.
   Formed by mixing; united; mingled; blended. See Mix, v. t.
   & i.
   [1913 Webster]

   Mixed action (Law), a suit combining the properties of a
      real and a personal action.

   Mixed angle, a mixtilineal angle.

   Mixed fabric, a textile fabric composed of two or more
      kinds of fiber, as a poplin.

   Mixed marriage, a marriage between persons of different
      races or religions; specifically, one between a Roman
      Catholic and a Protestant.

   Mixed number, a whole number and a fraction taken together.


   Mixed train, a railway train containing both passenger and
      freight cars.

   Mixed voices (Mus.), voices of both males and females
      united in the same performance.
      [1913 Webster]

WordNet (r) 3.0 (2006):

mixed
    adj 1: consisting of a haphazard assortment of different kinds;
           "an arrangement of assorted spring flowers"; "assorted
           sizes"; "miscellaneous accessories"; "a mixed program of
           baroque and contemporary music"; "a motley crew"; "sundry
           sciences commonly known as social"- I.A.Richards [syn:
           assorted, miscellaneous, mixed, motley,
           sundry(a)]
    2: involving or composed of different races; "interracial
       schools"; "a mixed neighborhood" [syn: interracial,
       mixed]

Moby Thesaurus II by Grady Ward, 1.0:

107 Moby Thesaurus words for "mixed":
   adulterated, amalgamated, ambiguous, ambivalent, amphibious,
   assimilated, associated, assorted, blemished, blended, clashing,
   combinative, combinatory, combined, complex, composite, compound,
   compounded, conflicting, confused, conglomerate, conjoint,
   conjugate, conjunctive, connected, connective, consolidated,
   contradictory, damaged, dappled, defective, deficient, diverse,
   eclectic, equivocal, erroneous, fallible, faulty, fifty-fifty,
   found wanting, fused, half-and-half, half-bred, heterogeneous,
   hybrid, immature, impaired, imperfect, imprecise, impure,
   inaccurate, inadequate, incomplete, incorporated, indiscriminate,
   inexact, integrated, interbred, intricate, involved, ironic,
   joined, joint, jumbled, lacking, makeshift, many-sided, mediocre,
   medley, merged, mingled, miscellaneous, mongrel, motley, muddled,
   multifaceted, multifarious, multinational, multiracial,
   not perfect, off, one, opposing, opposite, partial, patchy,
   pluralistic, promiscuous, scrambled, short, sketchy, syncretic,
   syncretistic, syncretized, synthesized, tainted, thrown together,
   undeveloped, uneven, unfinished, united, unperfected, unsound,
   unthorough, varied, various, wanting



Bouvier's Law Dictionary, Revised 6th Ed (1856):

MIXED. To join; to mingle. A compound made of several simples is said to be
something mixed.