Pronunciation: (met'u-stā"bul, met"u-stā'-), [key]
1. Metall.chemically unstable in the absence of certain conditions that would induce stability, but not liable to spontaneous transformation.
2. Also,labile. Physics, Chem.pertaining to a body or system existing at an energy level (met'asta'ble state') above that of a more stable state and requiring the addition of a small amount of energy to induce a transition to the more stable state.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.