barrier Definition

something material that blocks or is intended to block passage

a natural formation or structure that prevents or hinders movement or action

a medieval war game in which combatants fight on foot with a fence or railing between them

a long broad sandy island lying parallel to a shore that is built up by the action of waves, currents, and winds and that protects the shore from the effects of the ocean

a coral reef roughly parallel to a shore and separated from it usually by a lagoon

a naturally occurring barrier created by the modification of brain capillaries (as by reduction in fenestration and formation of tight cell-to-cell contacts) that prevents many substances from leaving the blood and crossing the capillary walls into the brain tissues

a concrete slab 32 inches high with slanted sides that is used in tandem with others to block or reroute traffic or to divide highways

sound barrier

a sudden large increase in aerodynamic drag that occurs as the speed of an aircraft approaches the speed of sound

a layer of material (such as roofing paper or polyethylene film) used to retard or prevent the absorption of moisture into a construction (such as a wall or floor)

coral reef 1250 miles (2012 kilometers) long in the Coral Sea off the northeast coast of Queensland, Australia

a strong metal bar along the side of a road that prevents vehicles from driving off the road : guardrail