noun: 1. An artificial channel, stream, etc. 2. A valve or gate to control the flow of a liquid. 3. A body of water controlled by a sluice gate. verb tr.: 1. To let out, by or as if by, opening a gate. 2. To wash, flush, cleanse, etc. 3. To send logs, gold-bearing gravel, or other material down a sluice. verb intr.: To flow, as if from or through a sluice.