The Collaborative International Dictionary of English v.0.48:

payload \pay"load`\ (p[=a]"l[=o]d`) n.
   The part of a missile or torpedo that carries the explosive
   charge.

   Syn: warhead, load.
        [WordNet 1.5]

   2. The goods carried by a large vehicle.

   Syn: cargo, lading, freight, load, loading, shipment,
        consignment.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

payload
    n 1: the front part of a guided missile or rocket or torpedo
         that carries the nuclear or explosive charge or the
         chemical or biological agents [syn: warhead, payload,
         load]
    2: goods carried by a large vehicle [syn: cargo, lading,
       freight, load, loading, payload, shipment,
       consignment]