Metastable

Definition

• (of a state of equilibrium) stable provided it is subjected to no more than small disturbances. "the amount of supercooling a liquid can accept while remaining in metastable equilibrium is limited"
• (of a substance or particle) theoretically unstable but so long-lived as to be stable for practical purposes. "the occurrence of metastable olivine and deep earthquakes in subducting lithosphere"

Context

The metastability concept originated in the physics of first-order phase transitions. It then acquired new meaning in the study of aggregated subatomic particles (in atomic nuclei or in atoms) or in molecules, macromolecules or clusters of atoms and molecules. Later, it was borrowed for the study of decision-making and information transmission systems.

Also called a "repeller" by Mandelbrot in his discussion of attractors.