tailboard n a gate at the rear of a vehicle; can be lowered for loading Usage(s) The man mounted, with assistance, the tailboard of a truck, took a paper from his pocket. Sometimes he got lifts, sharing the rear hump of a burro with a friendly peon or clinging to the bouncing tailboard of a truck. Gene backed up to the curb and began to arrange the vegetables and fruit on packing boxes, along the running board, and on the tailboard. Synonym(s) tailgate