Definition of "spillway"

Absence of filtered undrains beneath spillways or behind walls.

1993, Loren Runar Anderson, Geotechnical practice in dam rehabilitation

On February 24, 319379 crosses the wrought-iron Carr Mill Viaduct with Northern's 1515 Liverpool Lime Street-Wigan North Western service, viewed from a spillway for the reservoir.

2023 May 31, “Feature Pictorial”, in RAIL, number 984, page 57, photo caption