Source : Webster's Revised Unabridged Dictionary (1913)

Decorum \De*cor"um\, n. [L. dec[=o]rum, fr. dec[=o]rus. See
   {Decorous}.]
   Propriety of manner or conduct; grace arising from
   suitableness of speech and behavior to one's own character,
   or to the place and occasion; decency of conduct; seemliness;
   that which is seemly or suitable.

         Negligent of the duties and decorums of his station.
                                                  --Hallam.

         If your master Would have a queen his beggar, you must
         tell him, That majesty, to keep decorum, must No less
         beg than a kingdom.                      --Shak.

   Syn: {Decorum}, {Dignity}.

   Usage: Decorum, in accordance with its etymology, is that
          which is becoming in outward act or appearance; as,
          the decorum of a public assembly. Dignity springs from
          an inward elevation of soul producing a corresponding
          effect on the manners; as, dignity of personal
          appearance.

Source : WordNet®

decorum
     n : propriety in manners and conduct [syn: {decorousness}] [ant:
          {indecorum}, {indecorum}]