unstable

[ uhn-stey-buhl ]

adjective

1. not stable; not firm or firmly fixed; unsteady.
2. liable to fall or sway.

   Synonyms: precarious

3. unsteadfast; inconstant; wavering:

   unstable convictions.

   Synonyms: vacillating

4. marked by emotional instability:

   an unstable person.

5. irregular in movement:

   an unstable heartbeat.

6. Chemistry. noting compounds that readily decompose or change into other compounds.

unstable

/ ʌnˈsteɪbəl /

adjective

1. lacking stability, fixity, or firmness
2. disposed to temperamental, emotional, or psychological variability
3. (of a chemical compound) readily decomposing
4. physics
   1. (of an elementary particle) having a very short lifetime
   2. spontaneously decomposing by nuclear decay; radioactive

      an unstable nuclide

5. electronics (of an electrical circuit, mechanical body, etc) having a tendency to self-oscillation

unstable

/ ŭn-stā′bəl /

1. Liable to undergo spontaneous decay into some other form. For example, the nucleus of uranium 238 atom is unstable and changes by radioactive decay into the nucleus of thorium 234, a lighter element. Many subatomic particles, such as muons and neutrons, are unstable and decay quickly into other particles.
2. See more at decay
3. Relating to a chemical compound that readily decomposes or changes into other compounds or into elements.
4. Relating to an atom or chemical element that is likely to share electrons; reactive.
5. Characterized by uncertain or inadequate response to treatment and the potential for unfavorable outcome, as the status of a medical condition or disease.

Derived Forms

• unˈstableness, noun
• unˈstably, adverb

Other Words From

• un·stable·ness noun
• un·stably adverb

Word History and Origins

Origin of unstable¹

First recorded in 1175–1225; Middle English; un- ¹ + stable ²

Synonym Study

See unsettled.

Example Sentences

Only Colbert can work through a “Your internet connection is unstable” warning popping up during a Zoom interview.

From Vox

There’s a long history of rural areas relying on one unstable source of income and on the desirability of natural resources.

From Outside Online

After that, spring would bring unstable ice, rising waters, and unsuitable conditions to trap fish owls.

From Popular-Science

If the universe turns out to be fundamentally unstable, a tiny bubble of the cosmos could convert to a more stable state.

From Science News

If the voltage goes too high or too low, the water itself becomes unstable.

From Science News For Students

Most of the think tanks thought that the situation in eastern regions of Ukraine would remain unstable for a long time.

From The Daily Beast

However, as they enter the current, the boat becomes unstable.

From The Daily Beast

You lethargic, unfocused, unstable, lazy, hazy, crazy time of year.

From The Daily Beast

Several people from the neighborhood told The Daily Beast the man was mentally unstable.

From The Daily Beast

The late 1960s proved to be the most civically unstable since the 1860s.

From The Daily Beast

Hence Napoleon was driven more and more to trust to the advice of the rash, unstable King of Naples.

From Project Gutenberg

Industrial society is therefore mobile, elastic, standing at any moment in a temporary and unstable equilibrium.

From Project Gutenberg

The bliss of lovers is so unstable, that in every case lovers have more woes than the moon has changes.

From Project Gutenberg

To me it is simply a medium, an unstable, oscillating medium of impetuous spiritual energies.

From Project Gutenberg

As a jailer he was in close touch with facts and knew by experience how unstable in these days was any man's power.

From Project Gutenberg

Related Words

• ambiguous
• changeable
• erratic
• fickle
• insecure
• irrational
• precarious
• risky
• rocky
• sensitive
• shaky
• slippery
• ticklish
• tricky
• uncertain
• unpredictable
• unsettled
• unsteady
• volatile
• weak