There is no rule. The term can be applied freely to plugs and sockets depending on the preference of the writer or speaker. Why do you think that there has to be an officially correct usage? English dictionaries have been descriptivist for about 150 years. Digital computers are a comparatively recent development.
The connector refers to the physical connection. In the case of USB connectors, it refers to both the plug and the socket that the plug goes into. If it's being used to refer to the socket only, it might be *assumed* that the device you are going to use with it has the plug on it lready. -Dave
Like others have said, the nomenclature depends on the application. Your question is therefore unclear--what do you mean by "socket" and "plug"?
For this application, find the answer to your question in chapter 6 of
is the generic term; it covers sockets, plugs, receptacles, etc...
I've used "plug" to mean "the thing that is at the end of a cord", and "receptacle" to mean "the thing that is mounted in the cabinet", and "socket" to mean "something at your house, but we don't have any in the plant".
Of course, when your electrician calls the thing in the cabinet a "socket" you don't argue with him unless you never want to get any work done again. Especially since he's probably been doing this for forty years and will teach you many valuable things if you listen...;)