unstable
The ladder felt unstable and wobbled under his weight.
The ladder was not firm or steady, causing it to shake.
likely to change or fail; not stable
The political situation in the country remains unstable.
The country's political situation is likely to change or fail.
Often describes systems, emotions, or conditions that are prone to disruption.
chemically reactive or physically insecure
Nitroglycerin is an unstable compound that can explode easily.
Nitroglycerin is a chemical compound that reacts easily and may explode.
In chemistry, describes substances that decompose or react violently.
emotionally or mentally disturbed
After the accident, he became emotionally unstable and needed therapy.
The accident caused him emotional distress, requiring professional help.
Refers to a person's mental state being easily disturbed or unpredictable.
Collocations
Pro Tip
Common Mistakes with 'Unstable'
Avoid using 'unstable' to describe people's personalities in formal contexts unless referring to mental health, as it can sound judgmental.
Gold Rule
When to Use 'Unstable'
Use 'unstable' for things that are physically shaky, emotionally unpredictable, or likely to fail. Do not use it for objects that are simply old or worn out.
Word Origin
From Middle English 'unstable', from Old French 'unstable', from Latin 'instabilis' (unsteady), from 'in-' (not) + 'stabilis' (firm, steady).
Usage Notes
Used to describe anything that lacks firmness, security, or predictability. Common in both physical and abstract contexts.