Final answer:
The method involving adjusting a thermometer based on the temperature at which water freezes is called calibration.
Step-by-step explanation:
The method involving adjusting a thermometer based on the temperature at which water freezes is called calibration. When calibrating a thermometer, the freezing point of water is used as a reference temperature. For example, on the Celsius scale, the freezing point of water is defined as 0 °C, and on the Fahrenheit scale, it is defined as 32 °F.