The simplest way to answer that is to look it up 🙂 That’s how you expand your knowledge, by looking for other words containing that “chunk”, that root, and trying to relate them with the known ones! For example if you check here: http://dictionary.reference.com/browse/panegyric you will find that, just as with pandemonium, the origin does include the “pan” we know and love, though not directly in the present-day meaning.
CAT-holics 
How about panegyric?
The simplest way to answer that is to look it up 🙂 That’s how you expand your knowledge, by looking for other words containing that “chunk”, that root, and trying to relate them with the known ones! For example if you check here: http://dictionary.reference.com/browse/panegyric you will find that, just as with pandemonium, the origin does include the “pan” we know and love, though not directly in the present-day meaning.
regards
J