an opening or hollow that forms a holder for something or into which something fits, e.g. any of various bony hollows in the body
the eye socket
a device in an electrical circuit into which a plug, bulb, etc can be fitted
a short tube that is shaped at one end to fit over a nut or bolt and has a square hole at the other end to receive the driving shaft of a tool
[Middle English soket from Anglo-French, dimin of Old French soc ploughshare, of Celtic origin]