(Bayonet Nut Coupling) A commonly used plug and socket for audio, video and networking applications that provides a tight connection. Using a mount somewhat similar to the way a bayonet (knife) is mounted onto the end of a rifle, BNCs are used to connect a variety of different coaxial cable types. After the plug is inserted, it is turned, causing pins in the socket to be pinched into a locking groove on the plug.

A Whole Lotta Names
There are numerous definitions of the BNC acronym, including Bayonet Neill-Concelman (after its inventors), Barrel Nut Connector, Bayonet Nipple Connector, Bayonet Navy Connector, Baby N Connector, British Naval Connector and British National Connector. See A/V ports, coaxial cable and plugs & sockets.