"Battle rifle" is not a formally recognized term like "assault rifle", but it is widely used, and I think it has a lot of utility. It is intended to differentiate between intermediate-caliber and full-power military rifles, and to that end I propose these four criteria to define a "battle rifle":

1 - A military style or pattern rifle
2 - Intended primarily to be fired from the shoulder
3 - Self-loading (either semi- or fully automatic)
4 - Chambered for a full power rifle cartridge