pandaemonium

In 1667, John Milton published Paradise Lost, his epic poem about the fall of Satan and humanity. In Book I, the fallen angels build a magnificent palace in hell and name it Pandæmonium—from Greek pan ('all') and daimonion ('demon'). It was the 'place of all demons,' the capital of hell, Satan's parliament building.

Milton didn't just describe a place—he coined a word. Pandemonium was his invention, built from Greek roots but assembled in English for the first time. The word was so vivid that it immediately escaped the poem and entered common usage.

By the 1700s, pandemonium had been lowercase'd and generalized—it no longer meant a specific building in hell but any place of wild disorder or uproar. A riot was pandemonium. A crowded marketplace was pandemonium. The devil's parliament became a metaphor for earthly chaos.

Today, pandemonium is used casually for any noisy, chaotic situation—pandemonium broke out, utter pandemonium, scenes of pandemonium. Most speakers have no idea they're quoting Milton, or that the word was once a proper noun naming a very specific address in hell.