Human computer
For three hundred years a computer was a person with paper, a pencil and one operation to perform over and over.
The word named a job long before it named a machine. From 1767 Nevil Maskelyne organised the Nautical Almanac so that every table was worked twice by two people independently and reconciled by a third — error checking through redundancy, a couple of centuries before the computer. Pay was by the page and the work was done at home.
It went industrial in the twentieth century. The Harvard Observatory computers classified stellar spectra from the 1880s, and the Mathematical Tables Project in New York employed some 450 people from 1938 under Gertrude Blanch. Most of them knew only the four basic operations, so Blanch decomposed each calculation into steps a single person could execute without understanding the whole. That decomposition is what would later be called a program.
The occupation disappeared into the machines it had named. When ENIAC needed programming, the six programmers were drawn from the pool computing ballistics trajectories by hand — they were the only people who already knew what the machine was supposed to do.