noun

1. Obsolete a fortress, stockade, etc. for defending an entrance or gate
2. a thing that prevents passage or approach; obstruction, as a fence, wall, etc.
3. anything that holds apart, separates, or hinders racial barriers, barriers to progress
4. a customs gate on a country's border
5. ice shelf
6. a high fence of stakes enclosing the area in which a tournament of knights was held; lists
7. Horse Racing the movable gate used to keep the horses in line at the starting point

Etymology: ME barrere < OFr barriere < barre, bar