Wave speed

Wave speed is a wave property which may mean only one of several things:

which may refer to absolute value of:
phase velocity, the velocity at which a wave phase propagates at a certain frequency.
group velocity, the propagation velocity for the envelope of wave groups and often of wave energy. This is different from the phase velocity for dispersive waves.
signal velocity, or information velocity, which is the velocity at which a wave carries information.
front velocity, the velocity at which the first rise of a pulse above zero moves forward.