riser

UK: /ˈraɪzə^r/ US: /ˈraɪzɚ/ ,(rī′zər)

WordReference Random House Learner's Dictionary of American English © 2025

ris•er /ˈraɪzɚ/   n. [countable]

1. one who rises, esp. from bed:
   He's an early riser.
2. Building the vertical face of a stair step.
3. Building
   • a long low platform on which persons can stand to be seen better, as on a stage.
   • risers, [plural] a group of such platforms connected stepwise.

WordReference Random House Unabridged Dictionary of American English © 2025

ris•er  (rī′zər), n. 

1. a person who rises, esp. from bed:
   to be an early riser.
2. Building the vertical face of a stair step.
3. Building 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. Building 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. [Naut.]
   • a heavy strake of planking in the vicinity of the garboard strake in a wooden vessel.
   • rising (def. 10).

• 1350–1400; Middle English; see rise, -er¹

Collins Concise English Dictionary © HarperCollins Publishers::

riser / 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
4. a low platform placed on a stage to elevate a person or object