The word "computer" once meant a person employed to spend their day performing mathematical operations for various purposes, usually by means of pen-and-paper.

Human (ie. pre-Computer) computers were widely used in land wars in the era between the advent of radio communications and the invention of the first digital computers. A field officer would radio his position and the estimated position of his artillery target to a field office, which would relay it to an ordnance center. A huge staff of computers would receive reports like this, dance a mathematical jig, and reply by radio with firing coordinates. Of course, by the time the necessary information reached the field officer, it was quite likely his quarry would have moved, requiring another pass through this system. This is just one example of how the necessities of modern warfare have advanced the computing state of the art.