Source : Webster's Revised Unabridged Dictionary (1913)

Brass \Brass\, n.; pl. {Brasses}. [OE. bras, bres, AS. br[ae]s;
   akin to Icel. bras cement, solder, brasa to harden by fire,
   and to E. braze, brazen. Cf. 1st & 2d {Braze}.]
   1. An alloy (usually yellow) of copper and zinc, in variable
      proportion, but often containing two parts of copper to
      one part of zinc. It sometimes contains tin, and rarely
      other metals.

   2. (Mach.) A journal bearing, so called because frequently
      made of brass. A brass is often lined with a softer metal,
      when the latter is generally called a white metal lining.
      See {Axle box}, {Journal Box}, and {Bearing}.

   3. Coin made of copper, brass, or bronze. [Obs.]

            Provide neither gold, nor silver, nor brass in your
            purses, nor scrip for your journey.   --Matt. x. 9.

   4. Impudence; a brazen face. [Colloq.]

   5. pl. Utensils, ornaments, or other articles of brass.

            The very scullion who cleans the brasses.
                                                  --Hopkinson.

   6. A brass plate engraved with a figure or device.
      Specifically, one used as a memorial to the dead, and
      generally having the portrait, coat of arms, etc.

   7. pl. (Mining) Lumps of pyrites or sulphuret of iron, the
      color of which is near to that of brass.

   Note: The word brass as used in Sculpture language is a
         translation for copper or some kind of bronze.

   Note: Brass is often used adjectively or in self-explaining
         compounds; as, brass button, brass kettle, brass
         founder, brass foundry or brassfoundry.

   {Brass band} (Mus.), a band of musicians who play upon wind
      instruments made of brass, as trumpets, cornets, etc.

   {Brass foil}, {Brass leaf}, brass made into very thin sheets;
      -- called also {Dutch gold}.

Source : WordNet®

brass
     n 1: an alloy of copper and zinc
     2: a wind instrument that consists of a brass tube (usually of
        variable length) blown by means of a cup-shaped or
        funnel-shaped mouthpiece
     3: the persons (or committees or departments etc.) who make up
        a body for the purpose of administering something; "he
        claims that the present administration is corrupt"; "the
        governance of an association is responsible to its
        members"; "he quickly became recognized as a member of the
        establishment" [syn: {administration}, {governance}, {governing
        body}, {establishment}, {organization}, {organisation}]
     4: impudent aggressiveness; "I couldn't believe her boldness";
        "he had the effrontery to question my honesty" [syn: {boldness},
         {nerve}, {face}, {cheek}]
     5: an ornament or utensil made of brass
     6: the section of a band or orchestra that plays brass
        instruments [syn: {brass section}]
     7: a memorial made of brass [syn: {memorial tablet}, {plaque}]