payload
This term centers on the distinction between the vehicle used for transport and the actual value or purpose being transported. In aerospace, it separates the fuel and structural weight of the rocket from the satellite or crew that justifies the mission's cost. In computing, the term shifts toward the distinction between the envelope and the letter. It describes the meaningful content of a data packet or a piece of malware, stripping away the technical headers, routing information, or delivery mechanisms that are necessary for transport but irrelevant to the final goal.
Countable when referring to a specific shipment or a specific piece of malware (e.g., a heavy payload). Uncountable when discussing the general concept of carrying capacity in engineering.
Meanings
The carrying capacity of an aircraft or launch vehicle, or the actual cargo being transported.
"The rocket's payload consisted of a weather satellite and several sensors."