A group of connection points, often wall or rack mounted in a wiring closet, used to mechanically terminate and interconnect twisted-pair building wiring.

The physical connection between patch panels or punch down blocks that facilitates connection from the workstation to the host or network.

You wire every desk with a bunch of wires. You punch one end of the wires into various plugs at the desk. You punch the other end onto some form of punchdown block. Then you bring the wires in from the telecom suppliers. You punch them down on another punchdown block. Now you have two sets of blocks - one for going to the office and those coming into the office from the outside. You now have to join them together. Joining them together is called cross connect. The reason you use cross connect wires rather than punching down lines directly to your phone system is that is can get messy. Moves, adds, and changes would confuse things and screw up connections. With short wires, it is easy to see where everything is connected. Cross-connect cables are also called Patch Cords.

A network device used by telecom carriers and large enterprises to switch and multiplex low-speed voice and data signals onto high-speed lines and vice versa. It is typically used to aggregate several E1/T1 lines into a higher-speed electrical or optical line as well as to distribute signals to various destinations.