polyphony=the maximum number of notes that can be played simultaneously. It can get complicated, but I believe this is the simplest explanation: If you had a keyb with 32 notes polyphony AND you had 32 fingers and all of your 32 fingers pressing the keys at the same time, you would be able to hear all the different notes.
polyphony does not mean better sounds, means more sounds heard at he same time.
wave rom=the bucket where sounds (waves) are located inside the keyb, Wave (R)ead (O)nly (M)emory