As part of an exam paper I've been using to revise with, I came across a question that simply says "What is parity?" Well I know vaguely what it is. Its to do with whether a wave is odd or even right? For example for cos and sin odd parity occurs because sin(-x) = -sin(x) and cos(-x) = cos(x) means that the function has even parity. But I what I don't know is how I would word the answer to the question "What is parity?". How would you do it? It only occurs (in the quantum-mechanical sense (very basic intro level)) if the wave function is centralised about the origin of the scale, right? Any hints as how to go about answering this would be appreciated.