backload

Short definition from Wiktionary

Noun

1. 1
   A load carried on the return journey of a delivery vehicle.

Verb

1. 1
   To load toward the back, or towards the end of a period.
2. 2
   To load (cargo, shipment, etc.) after unloading has been completed.
3. 3
   To transport further toward the rear of the theater of war.
4. 4
   To fill a syringe with solution from the plunger end of the barrel.