barrier

n. border, limit; obstacle, barricade

Barrier may refer to:Automatic full barriers, railwayCrash barrier, highwayLanguage barrier, culture/linguisticsNoise barrier, noise preventionSeparation barrier, prevents the movement of people across a certain line or border or to separate two populationsSound barrier, a physical boundary stopping large objects from becoming supersonicTrade barrier, restriction of trade by governmentVapor barrier, construction
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Barrier /bar·ri·er/ an obstruction. alveolar-capillary barrier , alveolocapillary barrier see under membrane. [more]Barrier - Community and Resources

Noun
1. a structure or object that impedes free movement
(hypernym) obstruction, obstructor, obstructer, impediment, impedimenta
(hyponym) bannister, banister, balustrade, balusters, handrail
2. any condition that makes it difficult to make progress or to achieve an objective; "intolerance is a barrier to understanding"
(synonym) roadblock
(hypernym) obstacle, obstruction
(hyponym) ideological barrier
3. anything serving to maintain separation by obstructing vision or access
(hypernym) mechanism
(hyponym) bar

(n.)
Any limit or boundary; a line of separation.
  

(n.)
An any obstruction; anything which hinders approach or attack.
  

(n.)
A fortress or fortified town, on the frontier of a country, commanding an avenue of approach.
  

(n.)
A fence or railing to mark the limits of a place, or to keep back a crowd.
  

(n.)
A carpentry obstruction, stockade, or other obstacle made in a passage in order to stop an enemy.