heat death

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

• noun The eventual dispersion of all of the energy within a physical system to a completely uniform distribution of heat energy, that is, to maximum entropy. The Second Law of Thermodynamics predicts heat death for all macroscopic physical systems.

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

• noun physics The state of a thermodynamic system having reached a maximum entropy; temperature is uniform throughout, and no energy is available to do work