What is Barrier?
{{wiktionary}} '''Barrier''' may refer to: * [[Breakwater]], a barrier on a coast to protect a harbour from ocean currents and waves * [[Defensive wall]], built to protect against an attack * [[Blood–brain barrier]], a separation of circulating blood and the brain extracellular fluid * Barrier reef, a type of [[coral reef]] running along a coast ** [[Belize Barrier Reef]], off the coast of Belize ** [[Great Barrier Reef]], off the coast of Queensland in north-east Australia * [[Dam]] {{disambiguation}}