The Collaborative International Dictionary of English v.0.48:

closed \closed\ adj.
   1. having an opening obstructed. [Narrower terms: blind]
      Also See: obstructed, sealed, shut, unopen,
      closed. Antonym: open.
      [WordNet 1.5]

   2. (Math.) of a curve or surface: having no end points or
      boundary curves; of a set: having members that can be
      produced by a specific operation on other members of the
      same set; of an interval: containing both its endpoints.
      open
      [WordNet 1.5]

   3. Being in a position to obstruct an opening; -- especially
      of doors. [Narrower terms: fastened, latched] Also See:
      closed. Antonym: open.

   Syn: shut, unopen.
        [WordNet 1.5]

   4. having skin drawn so as to obstruct the opening; -- used
      of mouth or eyes. Opposite of open. he sat quietly with
      closed eyes [Narrower terms: blinking, winking;
      compressed, tight; squinched, squinting]

   Syn: shut.
        [WordNet 1.5]

   5. requiring union membership; -- of a workplace; as, a
      closed shop. [prenominal]
      [WordNet 1.5]

   6. closed with shutters.
      [WordNet 1.5]

   7. hidden from the public; as, a closed ballot.
      [WordNet 1.5]

   8. not open to the general public; as, a closed meeting.
      [WordNet 1.5]

   9. unsympathetic; -- of a person's attitude. a closed mind
      unreceptive to new ideas
      [WordNet 1.5]

   10. surrounded by walls. a closed porch

   Syn: closed in(predicate).
        [WordNet 1.5]

   11. made compact by bending or doubling over; as, a closed
       map.

   Syn: folded.
        [WordNet 1.5]

   12. closed or fastened with or as if with buttons. [Narrower
       terms: buttoned (vs. unbuttoned)]
       [WordNet 1.5]

   13. not engaged in activity; -- of an organization or
       business establishment. the airport is closed because of
       the weather; the many closed shops and factories made the
       town look deserted

   Syn: shut down.
        [WordNet 1.5]