View synonyms for unstable


[ uhn-stey-buhl ]


  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.


/ ʌnˈsteɪbəl /


  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


/ ŭn-stābəl /

  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.

Discover More

Derived Forms

  • unˈstably, adverb
  • unˈstableness, noun

Discover More

Other Words From

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

Discover More

Word History and Origins

Origin of unstable1

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

Discover More

Synonym Study

Discover More

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.

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

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

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

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

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

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

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

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

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

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

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

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

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