Bumping is the airline practice of denying boarding to confirmed passengers who hold tickets on a specific flight, due to an oversold condition. The carrier will ask for volunteers to
take later flights, and will normally provide some sort of compensation in the form of vouchers or tickets for future travel. Rules for when compensation must be provided are complicated; ask the ticket agent for a copy of that carrier's rules, as each has their own set of guidelines. Some folks have managed to get bumped regularly in order to collect compensation - elevating the process to an art form !
Other definition:
Bumping is the practice of denying boarding to a confirmed passenger on an overbooked flight.
Other definition:
Bumping is the practice of removing confirmed passengers from overbooked flights.
Other definition:
Bumping is the passengers that are denied a seat on the flight they originally
booked on due to a flight being oversold. They will then be `bumped' to
another flight.