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unstable

 - 4 dictionary results

un⋅sta⋅ble

  [uhn-stey-buhl]
Use unstable in a Sentence
–adjective
1. not stable; not firm or firmly fixed; unsteady.
2. liable to fall or sway.
3. unsteadfast; inconstant; wavering: unstable convictions.
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.
Origin:
1175–1225; ME; see un- 1 , stable 2

Related forms:
un⋅sta⋅ble⋅ness, noun
un⋅sta⋅bly, adverb

Synonyms:
2. precarious. 2, 3. See unsettled. 3. vacillating.
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
Cite This Source Link To unstable
un·sta·ble   (ŭn-stā'bəl)   
adj.   un·sta·bler, un·sta·blest

    1. Tending strongly to change: unstable weather.

    2. Not constant; fluctuating: unstable vital signs.

    3. Fickle.

    4. Lacking control of one's emotions; marked by unpredictable behavior.

    5. Decomposing readily.

    6. Highly or violently reactive.

    7. Decaying with relatively short lifetime. Used of subatomic particles.

    8. Radioactive.

    1. Fickle.

    2. Lacking control of one's emotions; marked by unpredictable behavior.

    3. Decomposing readily.

    4. Highly or violently reactive.

    5. Decaying with relatively short lifetime. Used of subatomic particles.

    6. Radioactive.

  3. Not firmly placed; unsteady: an unstable ladder.

  4. Chemistry

    1. Decomposing readily.

    2. Highly or violently reactive.

    3. Decaying with relatively short lifetime. Used of subatomic particles.

    4. Radioactive.

  5. Physics

    1. Decaying with relatively short lifetime. Used of subatomic particles.

    2. Radioactive.

un·sta'ble·ness n., un·sta'bly adv.
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Word Origin & History

unstable 
c.1225, "apt to move," from un- (1) "not" + stable (adj.). Cf. M.H.G. unstabel. Meaning "liable to fall" is recorded from c.1300; sense of "fickle" is attested from c.1290.
Online Etymology Dictionary, © 2001 Douglas Harper
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Medical Dictionary

Main Entry: un·sta·ble
Pronunciation: -'stA-b&l
Function: adjective
: not stable: as a : characterized by frequent orunpredictable changes unstable condition> b : readily changing (as by decomposing) in chemical composition or biological activity c : characterized by inability to control the emotions
Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
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