Average velocity has two parts: Its magnitude (size) and its direction.
Its magnitude is
(straight-line distance between start-point and end-point, regardless of the route that's actually followed from start to finish) divided by (time taken to travel from start to finish).
Its direction is
(direction from start-point to end-point)
Notice that straight from this definition, the average velocity of going around a full circle is zero, no matter how fast you traveled. That's because the size of the average velocity is calculated from the straight-line distance from start-point to end-point, and that's zero if you finish at the same point you started from.