Gate (noun)

1. A barrier or enclosing structure used to block passage or control access.
2. A doorway or passageway that provides access to an enclosed area or building.
3. A frame or grillwork in or around which a fence or wall is set.
4. A frame that holds the blade of a saw.
5. A valve or switch controlling a flow or passage of fluid or electric current.

Origin:

Middle english, from old norse gat; akin to old high german gazza gully.

Examples:

1. The gate to the garden was locked.
2. The gate was closed to prevent the cattle from escaping.
3. The entrance gate to the castle was grand and imposing.
4. The gate on the saw was adjusted to the correct width.
5. The gate on the oil pipeline was shut off to stop the leak.