Meaning & Definition of Unstable in English

1. Lacking stability or fixity or firmness

• "Unstable political conditions"

• "The tower proved to be unstable in the high wind"

• "An unstable world economy"

2. Highly or violently reactive

• "Sensitive and highly unstable compounds"

3. Affording no ease or reassurance

• "A precarious truce"

4. Suffering from severe mental illness

• "Of unsound mind"

5. Disposed to psychological variability

• "His rather unstable religious convictions"

6. Subject to change

• Variable

• "A fluid situation fraught with uncertainty"

• "Everything was unstable following the coup"