freezing point

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The temperature at which a liquid of specified composition solidifies under a fixed pressure, usually standard pressure.
• noun The temperature at any fixed pressure at which the liquid and solid phases of a substance of specified composition are in equilibrium.

from The Century Dictionary.

• noun The temperature at which a liquid freezes; loosely, the temperature at which ice melts.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun the temperature at which a liquid freezes, and the solid and liquid phases are in equilibrium; normally the same as the melting point

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the temperature below which a liquid turns into a solid