ice point

n.
The temperature, equal to 0°C (32°F), at which pure water and ice are in equilibrium in a mixture at 1 atmosphere of pressure.

The temperature at which liquid and solid water are in equilibrium under atmospheric pressure. The ice point is by far the most important “fixed point” for defining temperatures scales and for calibrating thermometers. A closely related point is the triple point, which has gained favor as the primary standard since it can be attained with great accuracy in a simple closed vessel, isolated from the atmosphere. See also Triple point.

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