/ruy"zeuhr/ , n.
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. Metall. a chamber or enlarged opening at the top of a mold for allowing air to escape or adding extra metal.
6. Naut.
a. a heavy strake of planking in the vicinity of the garboard strake in a wooden vessel.
b. rising (def. 10).
[ 1350-1400; ME; see RISE, -ER 1 ]