melting point

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

• noun The temperature at which a solid becomes a liquid at a fixed pressure, usually standard pressure.
• noun The temperature at which a solid and its liquid are in equilibrium, at any fixed pressure.

from The Century Dictionary.

• noun The point or degree of temperature at which a solid body melts; the point of fusion or fusibility. See fusion.

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

• noun chemistry The temperature at which the solid and liquid phases of a substance are in equilibrium; it is relatively insensitive to changes in pressure

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

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