It is omega, and looks a little like w.

In physics, omega stands for angular velocity.

w = dθ /dt where θ is angular displacement and t is time.

In many electricity/magnetism formulae, 2*pi*w is found.

The unit of angular velocity is radians and 2*pi radians is equal to 360 degrees.

Interestingly, alpha is angular acceleration, dw/dt or d²θ /dt².

The Greek alphabets are used to represent various parameters in Physics, like mu is refractive index, rho is specific gravity (and specific resistance too), lambda is wavelenght etc.