This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

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n. A channel for an overflow of water, as from a reservoir.

n. A path designed to take away overflow safely.

n. A sluiceway or passage for superfluous water in a reservoir, to prevent too great pressure on the dam.

n. A passage for surplus water from a dam.

n. a channel that carries excess water over or around a dam or other obstruction

"The spillway is located on the right bank, and it has 14 segmented sluice-gates with a total discharge rate of 62,200 cubic meters per second."

conduit   

fence-post    by-lane    curb-to-curb    ramping    undercarriage    bollard    lanai    driller    weir    millrace