also: back away · BASH
A read play run backwards: the back runs one way and the quarterback keeps the other. Recent enough that usage is not fully settled.
A read play with the two paths reversed relative to a standard zone read. The back's run goes one direction and the quarterback's keep goes the other, so the read defender is being asked to choose between two things moving apart rather than two things going the same way.
The name is generally given as an abbreviation of back away, which describes what the back does. It is a comparatively recent addition to the read family and coaches do not all use it identically, so this entry states the shape rather than a fixed definition.
back awayzone read, RPOThe candidate list flags this one as recent and worth checking, and that caution is kept here rather than dropped. If a source and a coach disagree about what bash means, the coach's room usage wins for his room.