means The network of conductive cables and connections that carries electricity (or signals) through a building, device, or machine.

from From 'wire,' an Old English word ('wir') for a thin metal thread, with deep Germanic roots and likely cousins across the old languages — all pointing back to a sense of something twisted or drawn out into a slender strand. The metalworker's craft of pulling soft metal through ever-smaller holes to make thread gave us the noun; the '-ing' turned it into the act and the result, so 'wiring' became both the doing and the done — the whole tangled web behind the wall. The electrical sense rode in on the 19th-century arrival of the telegraph and the lightbulb, when wire stopped merely binding things and started carrying power.