[1] : The Collaborative International Dictionary of English v.0.48

barrier \bar"rier\, n. oe. barrere, barere, f. barri`ere,
   fr. barre bar. see bar, n.
   1. fort. a carpentry obstruction, stockade, or other
      obstacle made in a passage in order to stop an enemy.
      1913 webster

   2. a fortress or fortified town, on the frontier of a
      country, commanding an avenue of approach.
      1913 webster

   3. pl. a fence or railing to mark the limits of a place, or
      to keep back a crowd.
      1913 webster

            no sooner were the barriers opened, than he paced
            into the lists.                       --sir w.
                                                  scott.
      1913 webster

   4. any obstruction; anything which hinders approach or
      attack. "constitutional barriers." --hopkinson.
      1913 webster

   5. any limit or boundary; a line of separation.
      1913 webster

            'twixt that instinct and reason, what a nice
            barrier                              --pope.
      1913 webster

   barrier gate, a heavy gate to close the opening through a
      barrier.

   barrier reef, a form of coral reef which runs in the
      general direction of the shore, and incloses a lagoon
      channel more or less extensive.

   to fight at barriers, to fight with a barrier between, as a
      martial exercise. obs.
      1913 webster
see also:
bar barrier gate barrier reef to fight at barriers 

[2] : WordNet (r) 2.0

barrier reef
     n : a long coral reef near and parallel to the shore

Barrier Reef >> B Words
Barrier Reef, definition of term: Barrier Reef
barrier+reef_pag1.html

Reef >> R Words
Reef, definition of term: Reef
reef_pag1.html

Barrier >> B Words
Barrier, definition of term: Barrier
barrier_pag1.html

Barrier Reefs >> B Words
Barrier Reefs, definition of term: Barrier Reefs
barrier+reefs_pag1.html

Trade Barrier >> T Words
Trade Barrier, definition of term: Trade Barrier
trade+barrier_pag1.html

Sound Barrier >> S Words
Sound Barrier, definition of term: Sound Barrier
sound+barrier_pag1.html

Coral Reef >> C Words
Coral Reef, definition of term: Coral Reef
coral+reef_pag1.html

Sonic Barrier >> S Words
Sonic Barrier, definition of term: Sonic Barrier
sonic+barrier_pag1.html