What does the term "gauge pressure" specifically refer to?

Gauge pressure specifically refers to the pressure measured relative to atmospheric pressure. This means that when a gauge reads a certain value, it indicates how much higher or lower the pressure in the system is compared to the atmospheric pressure surrounding it. For instance, if a tire pressure gauge reads 35 psi, it means the air inside the tire is at a pressure of 35 psi above the atmospheric pressure. This concept is crucial in various applications, such as in hydraulics, pneumatics, and other engineering disciplines, where understanding the true operating conditions of a system relative to the atmosphere is essential for safety and functionality.

The other options do not accurately define gauge pressure; absolute pressure measures total pressure, including atmospheric pressure; negative pressure refers to pressures below atmospheric pressure; and high-pressure readings do not specifically relate to the definition of gauge pressure.