riser

American  

[rahy-zer] / ˈraɪ zər /

noun

1. a person who rises, especially 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.

6. Nautical.

   1. a heavy strake of planking in the vicinity of the garboard strake in a wooden vessel.

   2. rising.

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riser British  

/ ˈraɪzə /

noun

1. a person who rises, esp from bed

   an early riser

2. the vertical part of a stair or step

3. a vertical pipe, esp one within a building

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Etymology

Origin of riser

Middle English word dating back to 1350–1400; rise, -er ¹