The Full Form of HOV is High-occupancy vehicle.

High-occupancy vehicle (HOV) lanes are one or more lanes of a roadway that have restrictions on use to encourage ridesharing and can reduce vehicle miles traveled (VMT). Rules for HOV lanes vary and are usually posted. Typically, HOV lanes are open to motor vehicles carrying two or more people, and sometimes access is open to motorcycles or vehicles that use alternative fuels (hybrid or electric vehicles). Access restrictions on HOV lanes can apply 24-hours a day or only during peak congestion periods. The goal of HOV lanes is to provide an incentive to use ridesharing and public transportation, remove congestion from normal lanes of travel, and improve overall traffic operations. In places with excess capacity on HOV lanes, high-occupancy toll (HOT) lanes have been implemented. These differ from HOV lanes in that motor vehicles carrying only one person can use these lanes for a fee. Users may be able to use HOT lanes at all times that HOV lanes are in operation or HOT lane use may be restricted during the most congested periods.