Definition of lobby:
(n) :
an entryway or waiting area;
vestibule; the class or group of people who try to lobby or influence public officials; collectively, lobbyists
"I had to wait in the lobby for hours before seeing the doctor."
(v) :
to attempt to influence (a public official or decision-maker) in favor of a specific opinion or cause
"for years, pro-life groups have continued to lobby hard for restrictions on abortion."