What is the physical meaning of the parity of a wavefunction?

[opous]

Can anyone help me understand what is meant by the "parity of a wavefunction"?

I know in terms of even/odd parity, that:

$$P \Psi(x,y,z) = \pm \Psi(x,y,z)$$

ie, P = +/- 1

But I don't know what "parity of a wavefunction" physically means...

 

[pam]

The P operator turns $${\vec r}\rightarrow -{\vec r}$$.

 

[malawi_glenn]

you can also relate this to ordninary functions.

P(cos(x)) = cos(-x) = cos(x) ; so cos is an even function -> Symmetric

P(sin(x)) = sin(-x) = -sin(x) ; so sin is an odd function -> Anti-Symmetric