- The definition of unstable is something that is prone to changing often, or a person with wild mood swings.
- When the weather changes from freezing to hot to freezing rapidly and without reason, this is an example of a time when it is unstable.
- When a person has a bad temper that can explode or flare up with no provocation at all, this is an example of a person who would be described as unstable.
unstable definition by Webster's New World
not stable; specif.,
- not fixed, firm, or steady; easily upset or unbalanced
- changeable; variable; fluctuating
- unreliable; fickle
- emotionally unsettled
- Chem. tending to decompose or change into other compounds
Origin: Middle English
unstable definition by American Heritage Dictionary
The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
adjective un·sta·bler, un·sta·blest
- a. Tending strongly to change: unstable weather.b. Not constant; fluctuating: unstable vital signs.
- a. Fickle.b. Lacking control of one's emotions; marked by unpredictable behavior.
- Not firmly placed; unsteady: an unstable ladder.
- Chemistry a. Decomposing readily.b. Highly or violently reactive.
- Physics a. Decaying with relatively short lifetime. Used of subatomic particles.b. Radioactive.
- un·staˈble·ness noun
- un·staˈbly adverb
unstable - Science Definition
- 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. See more at decay.
- Relating to a chemical compound that readily decomposes or changes into other compounds or into elements.
- Relating to an atom or chemical element that is likely to share electrons; reactive.
- Characterized by uncertain or inadequate response to treatment and the potential for unfavorable outcome, as the status of a medical condition or disease.