barrier

American  

[bar-ee-er] / ˈbær i ər /

noun

1. anything built or serving to bar passage, as a railing, fence, or the like.

   People may pass through the barrier only when their train is announced.

   Synonyms:

   impediment, hindrance, obstruction, wall, palisade

2. any natural bar or obstacle.

   a mountain barrier.

   Synonyms:

   impediment, hindrance, obstruction

3. anything that restrains or obstructs progress, access, etc..

   a trade barrier.

   Synonyms:

   impediment, hindrance, obstruction

4. a limit or boundary of any kind.

   the barriers of caste.

5. Physical Geography. an Antarctic ice shelf or ice front.

6. barrier beach.

7. History/Historical. barriers, the palisade or railing surrounding the ground where tourneys and jousts were carried on.

8. Archaic. a fortress or stockade.

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barrier British  

/ ˈbærɪə /

noun

1. anything serving to obstruct passage or to maintain separation, such as a fence or gate

2. anything that prevents or obstructs passage, access, or progress

   a barrier of distrust

3. anything that separates or hinders union

   a language barrier

4. 1. an exposed offshore sand bar separated from the shore by a lagoon

   2. ( as modifier )

      a barrier beach

5. (sometimes capital) that part of the Antarctic icecap extending over the sea

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Related Words

See bar ¹.

Etymology

Origin of barrier

First recorded in 1275–1325; Middle English, from Middle French barriere ( barre bar ¹ + -iere, from Latin -āria -ary ); replacing Middle English barrere, from Anglo-French, from Medieval Latin barrera

Explanation

Barriers are walls, either physical or metaphorical. They can block movement — the Great Wall of China was a barrier to block invading forces from entering. A window shade is a light barrier. Failing English is a barrier to getting into Harvard. When people are being excluded from joining a clique, you could say that the clique has erected a social barrier. When fighter jets fly faster than the speed of sound, they break through what feels like a wall in the sky called the sound barrier. The Green Monster at Fenway Park keeps Boston Red Sox fans from being able to watch games from outside the stadium — it's a barrier to sight. But when line drives hit the Green Monster, bouncing the ball back into left field, the Green Monster acts also a barrier to easy home runs.

Example Sentences

It originated from what scientists consider Australia's first 'Great Barrier Reef,' a Devonian era reef system located in the Kimberley region of northern WA.

From Science Daily • Mar. 12, 2026

"That included back-to-back events on Australia's Great Barrier Reef. Three more bleaching events have happened there since. We are seeing that reefs don't have time to recover properly before the next bleaching event occurs."

From Science Daily • Feb. 12, 2026

Australia's Great Barrier Reef, for instance, saw peak heat stress increase each year between 2014 and 2017.

From Barron's • Feb. 10, 2026

The Great Barrier Reef is headed for a "grim future" and will suffer a "rapid coral decline" by 2050 but parts may recover if global warming is kept below 2C, a new study has found.

From BBC • Nov. 5, 2025

I watched them play from a distance until a few minutes later, when her Barrier spell dissipated.

From "Ready Player One: A Novel" by Ernest Cline

Related Words

• barricade
• blockade
• boundary
• fence
• hurdle
• impediment
• limit
• obstacle
• railing
• roadblock
• wall