Thermal stability is the stability of a molecule at high temperatures; i.e. a molecule with more stability has more resistance to decomposition at high temperatures.
Thermal stability also describes, as defined by Schmidt (1928), the stability of a water body and its resistance to mixing. This is the amount of work needed to transform the water body (e.g. a lake) to a uniform water density. The Schmidt stability 'S' is commonly measured in Joule per square meter or g*cm/cm. Compare Stratification.
Further reading 
- Gwidon W. Stachowiak and Andrew W. Batchelor (2005). Engineering Tribology. Butterworth–Heinemann. pp. 39–40. ISBN 0-7506-7836-4.
- Schmidt, W. 1928. Über Temperatur und Stabilitätsverhältnisse von Seen. Geogr. Ann 10: 145 - 177.