A specific length of cable for sale that is terminated at each end with a plug.  Any telephone, audio, video or Ethernet cable with connectors at both ends is a patch cord.  See 
patch panel and 
pigtail.
An Ethernet Patch Cord
Patch cords come in various lengths from one to 100 feet.  Longer or custom-sized cables are made by cutting the required length from a spool and attaching the plugs with a tool specialized for that type of connector.