What does the abbreviation "psi" stand for?

The abbreviation "psi" stands for "pounds per square inch." This unit of measurement is commonly used to quantify pressure. It describes the amount of force (in pounds) exerted over an area of one square inch. Understanding this measurement is crucial in the context of air brake systems, as it helps technicians and operators monitor and manage the pressure within the braking systems effectively. Maintaining the correct psi levels is essential for ensuring the safety and performance of vehicles, particularly those equipped with air brakes.

The other options provide terms that either do not relate to pressure measurements or represent different concepts altogether, which highlights the specificity of the term "pounds per square inch" in this context.