early computers were just machines that were used to calculate, more precisely ,they were used to compute tables for the American Army. So came the name computer.
The word compute, acc. to Dictionary.com has the following origin:
1631, from Fr. computer, from L. computare "to count, sum up," from com- "with" + putare "to reckon," orig. "to prune." Computer used for person, 1646; mechanical calculating machine, 1897; and electronic machine, 1946 or 1941. In the modern meaning, "programmable digital electronic computer" is from 1945 (theoretical sense is from 1937, as Turing machine). ENIAC (1946) is usually considered the first. Computerese first recorded 1960.
Key: Fr. ->French
L. -> Latin