noun

• (mining) A long box or trough through which water flows, used for washing auriferous earth.
• (linguistics) An instance of wh-stranding ellipsis, or sluicing.

verb

• (transitive, rare) To emit by, or as by, flood gates.
  "Nigh on the plain, in many cells prepared, / That underneath had veins of liquid fire / Sluiced from the lake, a second multitude / With wondrous art founded the massy ore, / Severing each kind, and scummed the bullion-dross."
• (transitive) To wet copiously, as by opening a sluice
  "Nine - mile Creek has been dug out again and again , and has been sluiced three times"
• (transitive) To wash with, or in, a stream of water running through a sluice.
  "to sluice earth or gold dust in a sluice box in placer mining"
• (transitive, more generally) To wash (down or out).
  "[…] he did plot the Duke of Gloucester's death, / Suggest his soon-believing adversaries, / And consequently, like a traitor coward, / Sluiced out his innocent soul through streams of blood"