floodgate
1. [ noun ] a gate in a sluice that can control the flow of water
Synonyms: water_gate
Related terms: dam
2. [ noun ] something that restrains a flood or outpouring
Examples:

"suspension of surveillance opened the floodgates to illegal immigrants"

Related terms: restraint
3. [ noun ] regulator consisting of a valve or gate that controls the rate of water flow through a sluice
Synonyms: sluice_valve penstock head_gate water_gate sluicegate
Related terms: regulator aboiteau sluice
Similar spelling:   fledge
  fledged
  fledgeling
  fledgeless