flush 3 
(flŭsh)
(flŭsh)v. flushed, flush·ing, flush·es
v.tr.
1. To frighten (a game bird, for example) from cover.
2. To drive or force into the open: The police fired tear gas to flush out the terrorists.
v.intr.
To dart out or fly from cover.
n.
A bird or flock of birds that has been frightened from cover.
[Middle English flusshen.]