The Collaborative International Dictionary of English v.0.48:

Plugging \Plug"ging\, n.
   1. The act of stopping with a plug.
      [1913 Webster]

   2. The material of which a plug or stopple is made.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Plug \Plug\, v. t. [imp. & p. p. Plugged; p. pr. & vb. n.
   Plugging.]
   To stop with a plug; to make tight by stopping a hole.
   [1913 Webster]

   2. To briefly publicize or advertise, especially during a
      public event not specifically intended for advertising
      purposes; as, during the interview he plugged his new
      book.

   Syn: put in a plug for.
        [PJC]