Definitions

1. adjective

Having a property or state that is unstable but remains unchanged for a considerable time, often until a trigger or external influence causes a change.

“The metastable nucleus of the atom decayed quickly once it was struck by a high-energy particle.”

2. noun

A state or system that is metastable.

“The metastable state of the solution was crucial for the reaction to proceed as intended.”

3. noun

A substance or system that is metastable.

“The metastable material was found to be highly unstable and prone to rapid degradation.”