Originally Posted by 500 above
VR, or Rotation speed. The speed at which the airplane’s nosewheel leaves the ground.
Taken from this link. V speeds – Velocity-speeds
Since this is another thread for nitpicking, let's be precise. The below definition is from CS-23:
EASA CS 23.51 Take-off speeds
(a) For normal utility and aerobatic category
aeroplanes, the rotation speed VR, is the speed at
which the pilot makes a control input with the
intention of lifting the aeroplane out of contact
with the runway or water surface.
I'm more than sure that somebody with flight testing experience will come along and correct me.