rail

A rail is a long and thin piece of metal.

A rail is a long and thin bar along a stairway or path for people to slide their hand along while they walk.

Example: She put her hand on the railing beside the stairs so she wouldn't fall.

A rail is a surface where trains run on.

Example: The railway stretches across the country.

If you rail, you travel by railway.

If you rail someone, you sexually penetrate in a rough manner.