If the net work done on a particle is zero what is true about velocity and speed?

In one dimensional motion when work done by a force is zero does mean no change in velocity or speed is zero or both are constant. But if the motion is in more than one dimensions then W can be zero under three conditions magnitude of F = 0 , magnitude of S = 0 or vector F is perpendicular to vector S. If F is perpendicular to S then work done will be zero but velocity may change only in direction but speed will remain same. This is what happens in the case of uniform circular motion.