sluice

Short definition from Wiktionary

Noun

1. 1
   An artificial passage for water, fitted with a valve or gate, for example in a canal lock or a mill stream, for stopping or regulating the flow.
2. 2
   A water gate or floodgate.
3. 3
   Hence, an opening or channel through which anything flows; a source of supply.
4. 4
   The stream flowing through a floodgate.
5. 5
   A long box or trough through which water flows, used for washing auriferous earth.
6. 6
   An instance of wh-stranding ellipsis, or sluicing.

Verb

1. 1
   To emit by, or as by, flood gates.
2. 2
   To wet copiously, as by opening a sluice
3. 3
   To wash with, or in, a stream of water running through a sluice.
4. 4
   To wash (down or out).
5. 5
   To flow, pour.
6. 6
   To elide the complement in a coordinated wh-question. See sluicing.