Barrier

Barrier is any obstacle, including fence, used to prevent movement into or access to a place. Anything that keeps people or things apart or prevents communication or progress is also called barrier, such as language, cultural, or geographical barrier etc.

The gate at a parking lot or anywhere else to regulate the movement of vehicles, typically one, an arm of which is raised or lowered is also called barrier, and also the starting gate of a racecourse.

Barrier is also the short name of any of the barrier islands.