Source : Webster's Revised Unabridged Dictionary (1913)

Lobby \Lob"by\, n.; pl. {Lobbies}. [LL. lobium, lobia, laubia, a
   covered portico fit for walking, fr. OHG. louba, G. laube,
   arbor. See {Lodge}.]
   1. (Arch.) A passage or hall of communication, especially
      when large enough to serve also as a waiting room. It
      differs from an antechamber in that a lobby communicates
      between several rooms, an antechamber to one only; but
      this distinction is not carefully preserved.

   2. That part of a hall of legislation not appropriated to the
      official use of the assembly; hence, the persons,
      collectively, who frequent such a place to transact
      business with the legislators; any persons, not members of
      a legislative body, who strive to influence its
      proceedings by personal agency