pandemonium (n.)
1667, Pandæmonium, in "Paradise Lost" the name of the palace built in the middle of Hell, "the high capital of Satan and all his peers," coined by John Milton (1608-1674) from Greek pan- "all" (see pan-) + Late Latin daemonium "evil spirit," from Greek daimonion "inferior divine power," from daimon "lesser god" (see demon).

Transferred sense "place of uproar" is from 1779; that of "wild, lawless confusion" is from 1865. Related: Pandemoniac; pandemoniacal; pandemonian; pandemonic.