"net-like arrangement of threads, wires, etc.," 1550s, from net (n.) + work (n.). Extended sense of "any complex, interlocking system" is from 1839 (originally in reference to transport by rivers, canals, and railways). Meaning "broadcasting system of multiple transmitters" is from 1914; sense of "interconnected group of people" is from 1947.
1887, "to cover with a network," from network (n.). From 1940 as "to broadcast over a (radio) network;" 1972 in reference to computers; 1980s in reference to persons. Related: Networked; networking.