There are many proper definitions for the word
riser.
As a noun.
1. A person who rises, esp. from bed: to be an
early riser.
2. The vertical face of a stair step.
3. Any of a group of long boards or narrow platforms that can be combined in stepwise fashion: The choir stood on a horseshoe of risers behind the orchestra.
4. A vertical pipe, duct, or conduit.
5.
Metallurgy. a chamber or enlarged opening at the top of a mold for allowing air to escape or adding extra metal.
As a adjective.
1. Advancing, ascending, or mounting.
2. Growing or advancing to adult years.
As an adverb.
1. Somewhat more than.
2. In approach of; almost; well-nigh.
Example for #3 as a noun: The choir stood on a
horseshoe of risers behind the orchestra.
Example for #1 as a adjective: Rising smoke.
Examples for #1 & #2 as a adverb are below.
#1:
The crop came to rising
6000 bushels.
#2: A lad rising sixteen.