cryoscopy

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

• noun A technique for determining the molal concentration of a solution by measuring the freezing point.

from The Century Dictionary.

• noun That department of physical chemistry which treats of the freezing or solidification of liquids and solutions; specifically, the determination of molecular weights of dissolved substances by the lowering of the freezing-point of their solutions in suitable solvents.

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

• noun the measurement of the freezing point of a liquid using a cryoscope
• noun chemistry the estimation of the molecular weight of a compound by measuring its effect on the freezing point of a solvent