What does metastable mean?
Metastable describes something that is temporarily stable but not truly secure. In physics and chemistry, the term refers to a state that can persist under particular conditions while remaining capable of changing into a more stable state when those conditions change. For example, a metastable molecular intermediate may exist long enough to be detected before breaking down into a lower-energy product. The idea is closely related to stability but differs from it in an important way: a stable system is in equilibrium, whereas a metastable system is only locally stable. Outside the sciences, the word is used more figuratively to characterize arrangements, conditions, or agreements that seem durable but could easily be disrupted. It is especially useful when describing a temporary balance whose continuation depends on circumstances remaining favorable.
adjectiveIn physics, chemistry, and related technical fields, metastable describes a state that appears stable under particular conditions but can readily change to a more stable state when those conditions are altered. More generally, it means temporarily stable or liable to change.
- In physics and chemistry, relating to or occupying a state that is stable under specified conditions but can transition to a more stable state.
- More generally, temporarily stable, uncertain, or liable to change.
"The molecule remained in a metastable state until the temperature rose enough to trigger a reaction."
"A metastable intermediate formed and then rapidly decomposed into the final product."
"The agreement was described as metastable, meaning that it could hold for a time without being secure against further dispute."
Metastable is the scientific label for a moment when nothing dramatic happens—yet a change is waiting in the wings.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does metastable come from?
Metastable was formed in English from the combining form meta-, meaning “beyond” or “change,” and stable, which comes from Latin stabilis, meaning “firm” or “steady.” Its scientific sense developed by analogy with a stable equilibrium to describe a local equilibrium that persists temporarily but is capable of changing. The related English words stable, stability, stabilize, and stabilization all derive from the same Latin root.
Related word forms
How metastable is actually used
The word is primarily formal and technical. It is common in scientific and academic writing but can also be used figuratively for arrangements, conditions, or agreements that appear secure but remain vulnerable to change.
Easily confused with metastable
A stable state is a true equilibrium, whereas a metastable state is only locally stable and can change to a more stable state under the right conditions.
An unstable state tends to change spontaneously, while a metastable state can persist for a time before changing.