a long pole, fence, wall, or natural feature, such as a mountain or sea, that stops people from going somewhere
The Great Wall was a barrier between China and its enemies.
The tall fence served as a physical barrier to keep intruders out of the private property.
Language can sometimes be a barrier to effective communication when people from different cultures try to understand each other.
The lack of financial resources can be a significant barrier to accessing quality healthcare in many parts of the world.