software

ohjelmisto puhekieltä encode Encoded computer instructions, usually modifiable (unless stored in some form of unalterable memory such as ROM).
1958, John W. Tukey, "The Teaching of Concrete Mathematics" in The American Mathematical Monthly, vol. 65, no. 1 (Jan. 1958), pp 1-9:

The "software" comprising the carefully planned interpretive routines, compilers, and other aspects of automative programming are at least as important to the modern electronic calculator as its "hardware" of tubes, transistors, wires, tapes and the like.

As originally conceived, the word "software" was merely an obvious way to distinguish a program from the computer itself. A program comprised sequences of changeable instructions each having the power to command the behavior of the permanently crafted machinery, the "hardware."