What does "decorum" mean?

Decorum: 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. 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.