1. (

• floodgate

) something that restrains a flood or outpouring; "suspension of surveillance opened the floodgates to illegal immigrants" ;

2. (

• sluicegate ,
• sluice_valve ,
• floodgate ,
• penstock ,
• head_gate ,
• water_gate

) regulator consisting of a valve or gate that controls the rate of water flow through a sluice ;