Barrier
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