Any ammunition fired by rifles. Larger and longer than a handgun cartridge, smaller than cannon shells. This tag applies to any calibers, ranging from intermediate cartridges like 5.56mm NATO, full-power rounds like 7.62mm NATO or larger ones fired by heavy machine guns such as the .50 BMG.
A decent rule of thumb is that if the cartridge's length is more than 3.5 times the diameter of the case, it lacks a distinct rim, usually has bottlenecked case and the bullet diameter is approximately a half inch or less, then it is most likely a rifle cartridge regardless of specific caliber.