Etymology

Noun

1. A place where all demons live; Hell.
   • 1674 — John Milton, Paradise Lost, Book I

     And Trumpets sound throughout the Host proclaim
     A solemn Councel forthwith to be held
     At Pandæmonium, the high Capitol
     Of Satan and his Peers.

2. Chaos; tumultuous or lawless violence.
   • 2004, Boston Globe, October 22

     Whenever you have violent pandemonium, there's the overwhelming possibility for panic and tragedy.

3. An outburst; loud, riotous uproar, especially of a crowd.

Noun

1. pandemonium, residence of all demons/devils, hell;
2. pandemonium, a 'hellish' chaos, notably terrible noise and disorder