The Collaborative International Dictionary of English v.0.48:

Gangway \Gang"way`\, n. [See Gang, v. i.]
   1. A passage or way into or out of any inclosed place; esp.,
      a temporary way of access formed of planks.
      [1913 Webster]

   2. In the English House of Commons, a narrow aisle across the
      house, below which sit those who do not vote steadly
      either with the government or with the opposition.
      [1913 Webster]

   3. (Naut.) The opening through the bulwarks of a vessel by
      which persons enter or leave it.
      [1913 Webster]

   4. (Naut.) That part of the spar deck of a vessel on each
      side of the booms, from the quarter-deck to the
      forecastle; -- more properly termed the waist. --Totten.
      [1913 Webster]

   Gangway ladder, a ladder rigged on the side of a vessel at
      the gangway.

   To bring to the gangway, to punish (a seaman) by flogging
      him at the gangway.
      [1913 Webster]

WordNet (r) 3.0 (2006):

gangway
    n 1: a temporary passageway of planks (as over mud on a building
         site)
    2: a temporary bridge for getting on and off a vessel at
       dockside [syn: gangplank, gangboard, gangway]
    3: passageway between seating areas as in an auditorium or
       passenger vehicle or between areas of shelves of goods as in
       stores [syn: aisle, gangway]