Riser (noun)

1. A person or thing that rises.
2. A vertical section of a stairway between two steps.

Origin:

Early 16th century: from rise + -er1.

Examples:

1. The riser on the stairway was too steep.
2. The riser in the stock market was a welcome change.
3. He was a riser in the company, quickly rising through the ranks.
4. The risers on the stage were used to elevate the performers.
5. The riser on the ladder made it easier to climb.