restrictor
nounUK /rɪˈstrɪktə/
US /rɪˈstrɪktər/
A thing that keeps something from going too far or getting too big.
The restrictor on the water pipe stops too much water from flowing out.
RELATED WORDS
OTHER MEANINGS
2. A device in an engine or pipe that controls how much air or fuel can pass through.
The mechanic installed a restrictor to reduce the engine's power.
3. A person or rule that limits what others are allowed to do.
The new law acts as a restrictor on noisy late-night parties.
4. A substance or tool used to slow down or hold back a chemical reaction.
The scientist added a restrictor to keep the reaction from speeding up.