There is no clear definition of the breaker-zone, but it can be defined as the zone extending seaward from the shoreline that is exposed to depth-limited breaking waves.
Definition of Breaker zone - further notes
The outer limit of the breaker-zone is called the Breaker line. However, the instantaneous width of the surf-zone varies with the instantaneous wave conditions. In this context we define the surf-zone as the zone valid for the yearly wave climate defined by the significant wave height HS,12h/y, which is the wave exceeded 12 hours per year. The width of the breaker/surf-zone can thus be defined as the width of the zone within which HS,12h/y breaks. The breaker/surf-zone is somewhat narrower than the littoral zone. It is evaluated that 80 to 90% of the yearly littoral transport takes place within the breaker or surf-zone.