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Webster 1913 Edition


Unstable

Un-sta′ble

,
Adj.
[Cf.
Instable
.]
Not stable; not firm, fixed, or constant; subject to change or overthrow.
Un-sta′ble-ness
,
Noun.
Chaucer.
Unstable equilibrium
.
See
Stable equilibrium
, under
Stable
.

Webster 1828 Edition


Unstable

UNSTA'BLE

,
Adj.
[l. instabilis.]
1.
Not stable; not fixed.
2.
Not steady; inconstant; irresolute; wavering. James 1.

Definition 2022


unstable

unstable

English

Adjective

unstable (comparative more unstable, superlative most unstable)

  1. Having a strong tendency to change.
    • 2013 August 3, Yesterday’s fuel”, in The Economist, volume 408, number 8847:
      The dawn of the oil age was fairly recent. Although the stuff was used to waterproof boats in the Middle East 6,000 years ago, extracting it in earnest began only in 1859 after an oil strike in Pennsylvania. [] It was used to make kerosene, the main fuel for artificial lighting after overfishing led to a shortage of whale blubber. Other liquids produced in the refining process, too unstable or smoky for lamplight, were burned or dumped.
  2. Fluctuating; not constant.
  3. Fickle.
  4. Unpredictable.
  5. (chemistry) Readily decomposable.
  6. (physics) Radioactive, especially with a short half-life.

Synonyms

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Related terms

Translations

Verb

unstable (third-person singular simple present unstables, present participle unstabling, simple past and past participle unstabled)

  1. (transitive) To release (an animal) from a stable.
    • 1992, Elizabeth Darracott Wheeler, Sir John Dodderidge, Celebrated Barrister of Britain, 1555-1628
      When the last tune of music floated from the fleet, he unstabled his quarter horse and headed for the coastal road leading west and north on his circuit.

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