PBR

PBR is a three-letter acronym that refers to

Patrol Boat Rigid, a type of river patrol boat used by the US Navy during the Vietnam War
Plant Breeders' Rights, a patented cultivar
Plastic baton round, a type of non-lethal projectile more commonly known as the plastic bullet
Pabst Blue Ribbon, a brand of beer
Pharma Bio-Research, a Dutch drug research company
Professional Bull Riders, a sport, circuit, and company for professional bull riding
Policy based routing
Packed Bed Reactors, they are also called Plug Flow Reactors (PFR) or Pebble Bed Reactors
Prespective Based Review, a software inspection style in the descipline of software engineering