Etymology of "computer" before computer referred to a machine

Before modern computers, the term computer was used to describe people who computed, and this term was indeed sometimes used as a job title or description. For instance, in an 1884 report of the U.S. Naval Observatory, a list of acknowledgements of assistance included these:

...Mr. Theo I. King throughout the year, in the grade of computer until April 20, 1897, and subsequently in the grade of assistant astronomer; Computer Frank B. Littell... Computer E. A. Boeger throughout the year; Computer G. K. Lawton ...

In fact the U.S. Civil Service had competitive examinations for the position of Computer. The 1890 test had sections on spelling, penmanship, copying, letter-writing, algebra, geometry, logarithms, and trigonometry. (The sample questions may be interesting to some.)

Computer was not just used for people, though; it came to be used for any tool which helped with computation. This was not just mechanical devices such as adding machines, but was also applied to sets of numeric tables and procedures published in books such as Screw Propeller Computer.

There probably was not much confusion when digital computers were coming into use, just as previously there was not a great deal of confusion between an adding machine, a book, and a civil servant. In the early years, computer was usually qualified by an adjective, e.g. electronic computer, at least at initial mention.

Yes, Computer was a formal job title¹. Astronomer Henrietta Swan Leavitt (discoverer of Cepheid variables) was originally employed as a computer at $10.50 a week. The job as computer was later outlawed¹, at least in the United States, and I imagine the usage as a description of a person abruptly ended as a result.

_{*1 Physicist Richard Muller in the UC Berkeley "Physics 10" (AKA "Physics for Future Presidents") course. I don't recall the exact date for the presentation, but it can be found (I will also try to look/listen for it).}

It was actually used in a way as a title for people, as can be seen here:

1927, J. B. S. Haldane, Possible Worlds and Other Essays, p. 173
Only a few years ago Mr. Powers, an American computer, disproved a hypothesis about prime numbers which had held the field for more than 250 years.

Here is a bit of the history of the word "computer" :

computer
1640s, "one who calculates," from compute. Meaning "calculating machine" (of any type) is from 1897; in modern use, "programmable digital electronic computer" (1945; theoretical from 1937, as Turing machine ). ENIAC (1946) usually is considered the first. Computer literacy is recorded from 1970; an attempt to establish computerate (adj., on model of literate ) in this sense in the early 1980s didn't catch on.

Human computers were in demand in several activities.

1. Financial and accounting.
   You can probably picture the cliché representation of accountants wearing a vest, a visor, a bowtie and sleeve garters. Large companies would hire an army of these to keep their books. Computing errors were expensive because everything was done with pen and paper and when the totals would not match, one had to try to narrow the error down by successive tallies and basically a lot of manual rechecks.

2. Artillery.
   On the battlefield there's rarely enough time to compute the elevation and other angles needed to point guns at the enemy line. So artillery pieces servants use firing tables (beside the fact that artillery crews have few mathematicians). The higher the range of the gun, the more precise the table must be. So that before the advent of electronic computers, the army would employ a large number of human computers who would prepare thick books of abacuses in preparation for real or drill firing.
   Here is a quote from a well written blog entry.

   Their results would be published in ballistic "firing tables" published in gunnery manuals. During World War II the U.S. military scoured the country looking for (generally female) math majors to hire for the job of computing these tables. But not enough humans could be found to keep up with the need for new tables. Sometimes artillery pieces had to be delivered to the battlefield without the necessary firing tables and this meant they were close to useless because they couldn't be aimed properly. Faced with this situation, the U.S. military was willing to invest in even hair-brained schemes to automate this type of computation.

In several cases though, some kind of mechanical device was used to automate the computations. In fact the army was at the forefront of the research in mechanical and then electronic computing.

Of course, the rapid introduction of electronic computers quickly spelled the end of this profession and many people had to reconvert to related activities.

If you are interested in more of these, you can download the first chapter of the book "Computing Before Computer" which is freely available online.

Computer has Greek origin: when Thales went to Egypt to count the Great Pyramyd of Cufu, he was asked to solve the problem of re-calculating the limits of the farms after the Nile floods. He put sticks alongside the cost of Nile and on each of them he tied ropes in knots of equal distances. So they used this method of ropes in knots of equal distance to count, to measure. A new word was created in Greek on 6th century BC: Κομβέω - Κομβώ: to count with knots (Comveo). Soon the Latins took the word and named it Compasso: to calculate. They used to shout out loud when they calculated, so it was also simmilar to show-off combaso, oή compasso. During the centuries the word was Compute, (to count, to count with knots) and today we have the Computers. The Greek origin is clear Κομβώ, Compute. This method was used in navigation and we have the nautical knots, and the compass.