In the uniform linear motion the vector velocity v is constant, because the acceleration is zero. In the uniform circular motion, the absolute value of the vector velocity `|v|` is constant, but its direction is always changing because this time there is a nonzero acceleration `a_(cp)` that is directed towards the center of the circle representing the trajectory.
However there is one vector quantity in the circular motion that is analog to the linear velocity and that does not change. Its name is angular speed `omega` and it is defined as a vector is such a way that
`v = omega xx R`
Here, all three quantities are vectors and `xx` represent the vectorial (cross) product.
Similar to the linear speed that represents the space traveled in the time unit, the angular speed represent the angle with which the position has changed in the time unit. It is measured is `(rad)/s` .
For a body moving uniform counterclockwise in a circle the angular speed vector `omega` will be perpendicular to the plane of the circle (representing the trajectory) and directed upwards. The figure is attached.