a person who rises, esp. from bed

to be an early riser.

the vertical face of a stair step.

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.

a vertical pipe, duct, or conduit.

Metallurgy . a chamber or enlarged opening at the top of a mold for allowing air to escape or adding extra metal.

Nautical .

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

rising ( def. 10 ) .