Stair (noun)

1. A set of steps leading from one floor of a building to another, typically inside the building.
2. A step or steps, especially a set of steps between one floor of a building and another.

Origin:

From the old english word stæger, meaning "a stair or ladder".

Examples:

1. I walked up the stairs to the second floor.
2. The stairway was narrow and steep.
3. The stair rail was loose and needed to be fixed.
4. The stair carpet was worn and needed to be replaced.
5. The stair case was grand and impressive.