noun
water jacket
A casing or compartment through which water circulates to cool or heat something, such as an engine or laboratory equipment.
エンジンのシリンダー周りにはウォータージャケットが設けられている。
A water jacket is provided around the engine cylinders.
実験では、反応容器をウォータージャケットで一
In the experiment, the reaction vessel was kept at a constant temperature using a water jacket.