It would seem that specific velocity labels are relative. I believe that the terms are applied to each caliber and the intended purpose weapon in question. The grenade launcher round mentioned above is a good example. In that case they designate shoulder-fired versus machine-fired. In the 1950's the U.S. Army referred to Tungsten-Cored rounds for the 76mm and 90mm tank guns as "Hypervelocity" with velocities of 3,400 fps and 3,350 respectively. They were labeled HVAP-T rounds, and the words Hypervelocity and the actual velocity were printed on the side of the case. In this instance, the prior heavy shot antitank rounds were considered High Velocity at 2,800 fps, and the rounds that were 600 fps faster were the Hypervelocity ones, but the Tungsten core was also required to make the definition.
If you refer to 22 Rimfire ammo, you can buy "Subsonic" for use with suppressors, "Standard" Velocity for use in target shooting competition, and "High" Velocity for hunting and informal target practice or "plinking". If you refer to the U.S. Navy's Rail Gun, everything that it fires, is considered "Hypervelocity" at 3 k/ps and above.