Source : Webster's Revised Unabridged Dictionary (1913)

Hub \Hub\, n. [See 1st {Hob}.]
   1. The central part, usually cylindrical, of a wheel; the
      nave. See Illust. of {Axle box}.

   2. The hilt of a weapon. --Halliwell.

   3. A rough protuberance or projecting obstruction; as, a hub
      in the road. [U.S.] See {Hubby}.

   4. A goal or mark at which quoits, etc., are cast.

   5. (Diesinking) A hardened, engraved steel punch for
      impressing a device upon a die, used in coining, etc.

   6. A screw hob. See {Hob}, 3.

   7. A block for scotching a wheel.

   {Hub plank} (Highway Bridges), a horizontal guard plank along
      a truss at the height of a wagon-wheel hub.

   {Up to the hub}, as far as possible in embarrassment or
      difficulty, or in business, like a wheel sunk in mire;
      deeply involved. [Colloq.]

Source : WordNet®

hub
     n 1: the central part of a car wheel (or fan or propeller etc)
          through which the shaft or axle passes
     2: a center of activity or interest or commerce or
        transportation; a focal point around which events revolve;
        "the playground is the hub of parental supervision"; "the
        airport is the economic hub of the area"

Source : Free On-Line Dictionary of Computing

hub
     
         (By analogy with the hub of a wheel) A device
        connected to several other devices.
     
        In {ARCnet}, a hub is used to connect several computers
        together.  In a message handling service, a number of local
        computers might exchange messages solely with a hub computer.
        The hub would be responsible for exchanging messages with
        other hubs and non-local computers.
     
        (1995-01-16)