The term you're looking for is temperature. Temperature is a measure of the average kinetic energy of the particles in a substance. The higher the temperature, the faster the particles are moving and the more kinetic energy they have. Temperature can be measured using a variety of instruments, including thermometers, thermocouples, and resistance temperature detectors (RTDs).

The SI unit of temperature is the Kelvin (K). The Kelvin scale is based on absolute zero, which is the coldest temperature that is theoretically possible. Absolute zero is equal to -273.15 degrees Celsius or -459.67 degrees Fahrenheit.

The most common temperature scale is the Celsius scale (°C). The Celsius scale is based on the freezing point of water (0°C) and the boiling point of water (100°C) at sea level.

The Fahrenheit scale (°F) is also commonly used. The Fahrenheit scale is based on the freezing point of brine (32°F) and the boiling point of water (212°F) at sea level.