Definitions for "Modular Jack"
The outlet a telephone is plugged into. (RJ11)
The female connector used at the end of each horizontal cabling drop. Usually Modular Jacks utilize a 6 or 8 contact modular plug (on the patching side) and a 110, Krone, or other Insulation Displacement connection method (on the permanent horizontal wiring side).
A female connector (typically eight-position for data) that has become the standard interface for four-pair UTP copper cable. Also known as a RJ45 connector. This is found on the user-side ports and on the end of Modular Cable Assemblies. There are (unfortunately) two slightly different wiring patterns for this connector - T568A and T568B, and customers across the continent use one or the other. They cannot be mixed, requiring a set of Modular Cable Assemblies for each wiring pattern.