The term “Jacket Base” can refer to two different things.
In the context of clothing, it is the bottom of a jacket, all the way around the entire jacket. It is also called the hem. The jacket base can be made of a variety of materials, such as fabric, leather, or fur. It can be finished with a variety of techniques, such as stitching, pleating, or piping.
In the context of chemistry, a jacketed vessel is a container that is designed for controlling the temperature of its contents. It has a “jacket” around the vessel through which a cooling or heating fluid is circulated. This allows the temperature of the contents to be maintained at a constant level, regardless of the ambient temperature.