n (computing|networking) A networking device connecting multiple wires, allowing them to communicate simultaneously, when possible. Compare to the less efficient hub device that solely duplicates network packets to each wire.
n (telecommunication) A system of specialized relays, computer hardware, or other equipment which allows the interconnection of a calling party's telephone line with any called party's line.
n (BDSM) One who is willing to take either a sadistic or a masochistic role.