Meaning "set of correlated principles, facts, ideas, etc." first recorded 1630s. Meaning "animal body as an organized whole, sum of the vital processes in an organism" is recorded from 1680s; hence figurative phrase to get (something) out of one's system (1900). Computer sense of "group of related programs" is recorded from 1963. All systems go (1962) is from U.S. space program. The system "prevailing social order" is from 1806.
library classification system that organizes information into 10 broad areas subdivided numerically into progressively smaller topics, by 1885, named for Melvil Dewey (1851-1931) who proposed it 1876 while acting librarian of Amherst College. He also crusaded for simplified spelling and the metric system.
in visual arts, "arrangement of a figure so that the action of the upper body is strongly contrasted with that of the lower," 1903, from Italian contrapposto, past participle of contrapporre, from Latin contraponere "to place opposite, to oppose to" (see contraposition).
"computer operating system using a disk storage device," 1967, acronym of disk operating system.