Born in the corridors of industrial engineering before World War II, THROUGHPUT traveled back and forth a few times between descriptive neologism and itinerant metaphor.
After some years of disciplined life describing the pace and scope of work on old-fashioned assembly lines, or the delivery potential of fuel systems, the word made a mid-life career change and became a journeyman metaphor in the infant computer industry. It was such a hit there that it quickly grew to be a precisely defined technical term in its new field, infused with a tight new range of meanings.
That was the word’s first definitional leap, but it was a small one. Its original meaning was in most senses still intact: The processing of information really was a new application of the ideas of productive engineering and fuel delivery; the new meaning was not a metaphor but simply a new use for the original concept. Instead of people assembling machinery or pipes delivering fuel, machines were moving and assembling information. The point, though, remained a combination of transportation, assembly, and production.
But the computer pioneers soon lost control of the word (as of most of their once-specialized vocabulary, starting with THROUGHPUT’s parents, INPUT and OUTPUT). THROUGHPUT is now the universal metaphor for any interval between the moment anything is put into anything else and the moment it re-emerges, presumably altered.