👉 In physics, "proctodeum" refers to a device used for measuring the pressure in a fluid. It consists of a piston and a spring that are connected by a rubber or plastic tube. When the gas in the container is compressed, the spring exerts a force on the piston, which causes it to move back and forth. The amount of pressure exerted by this force can be measured using a device called a barometer, which is used for measuring atmospheric pressure.