A scupper is an opening in the side walls of an open-air structure, for purposes of draining water. They are usually placed at or near ground level, and allow rain or liquids to flow off the side of the open-air structure, instead of pooling within the walls.

There are two main kinds of scupper:

1. Ships have scuppers at deck level, to allow for ocean or rainwater drainoff
2. Buildings with railed rooftops can construct scuppers to let rainwater drain off, instead of pooling within the railing of the roof. Scuppers can also be placed in a parapet
   Parapet
   A parapet is a wall-like barrier at the edge of a roof, terrace, balcony or other structure. Where extending above a roof, it may simply be the portion of an exterior wall that continues above the line of the roof surface, or may be a continuation of a vertical feature beneath the roof such as a...
   
   , for the same purpose.

The transitive verb "to scupper" (British) means to overwhelm or destroy.
A scupper is also a name pirates would call other pirates that are lower ranks.