unstable
8 synonyms and 1 antonyms for unstable, grouped by meaning and by how common each one is.
Adj — Likely to shift, collapse, or change suddenly; not firmly fixed.
Synonyms
Less common
Still standard English, but they carry more weight.
Rare, literary or technical
Precise, but they will stand out — check the sense before using one.
Antonyms
How to use unstable
The word patterns that sound natural to a native speaker.
Etymology
From Middle English unstable; equivalent to un- (not) + stable.
Full origin of unstable →Frequently asked questions
What does “unstable” mean?
The word “unstable” means likely to shift, collapse, or change suddenly; not firmly fixed. In plain terms, not steady — physically shaky, emotionally erratic, or chemically prone to breaking down.
How do you pronounce “unstable”?
“Unstable” is pronounced uhn-STAY-buhl (/ʌnˈsteɪ.bəl/ in IPA).
How do you use “unstable” in a sentence?
Here is “unstable” used in a sentence: “The ladder felt unstable, so he climbed down carefully.”
What is another word for “unstable”?
Words with a similar meaning to “unstable” include unsteady and wobbly.
What is the opposite of “unstable”?
The opposite of “unstable” — its antonyms — is stable.
What part of speech is “unstable”?
“Unstable” is an adjective.
Is “unstable” a common word?
“Unstable” is a fairly common word in modern English.
How many meanings does “unstable” have?
“Unstable” has 3 distinct senses listed in this dictionary. The most common is: likely to shift, collapse, or change suddenly; not firmly fixed.
What is the difference between "unstable" and "unsteady"?
"Unstable" means likely to shift, collapse, or change suddenly and can apply to structures, situations, emotions, or substances. "Unsteady" is narrower and usually describes shaky physical movement or balance, as in unsteady hands or an unsteady walk.
What is the difference between "unstable" and "volatile"?
Both suggest a lack of steadiness, but "unstable" means prone to shifting, collapsing, or breaking down, while "volatile" emphasizes rapid, unpredictable, and often explosive change. A market can be unstable over time and volatile from moment to moment.
When is "unstable" used to describe a person?
When applied to a person, "unstable" usually means emotionally erratic or prone to sudden mood changes. This use can sound clinical or judgmental, so it is often softened in everyday speech to phrases like "going through a hard time."
How is "unstable" used in chemistry and physics?
In chemistry and physics, "unstable" describes a substance or particle prone to breaking down or decaying, sometimes radioactively. An unstable element or compound tends to react or transform readily rather than staying unchanged.