IPA: /ˌpændəˈmoʊniəm/
KK: /pænˈdɛmoʊniəm/
A situation or place that is filled with noise, confusion, and chaos.
When the concert ended, the crowd erupted into pandemonium, cheering and shouting.
Pandemonium is formed from "pan-" (meaning all) and "daemonium" (from Greek "daimonion", meaning lesser spirit or demon). The word originally referred to the place of all demons, hence it describes a chaotic or wild uproar involving many elements.
Think of 'all' ('pan-') spirits or 'demons' ('daemonium') coming together, which helps you remember that pandemonium means a chaotic situation with many elements.
No commonly confused words.