Double Occupancy Rate (Double-Occupancy Rate) is a rate used that bases the per-person charge on two to a room.
Other definition:
Double Occupancy Rate is the hotel room rate which implies that two persons can lodge in (share) the room. This rate is calculated per room and not per person or per bed.
Other definition:
Double-occupancy rate is the price per person for a Room to be shared with another person; the rate most frequently quoted in Tour brochures.