- not stable; not firm or firmly fixed; unsteady.
- liable to fall or sway.
- unsteadfast; inconstant; wavering: unstable convictions.
- marked by emotional instability: an unstable person.
- irregular in movement: an unstable heartbeat.
- Chemistry. noting compounds that readily decompose or change into other compounds.
Origin of unstable
Synonyms for unstable
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- lacking stability, fixity, or firmness
- disposed to temperamental, emotional, or psychological variability
- (of a chemical compound) readily decomposing
- (of an elementary particle) having a very short lifetime
- spontaneously decomposing by nuclear decay; radioactivean unstable nuclide
- electronics (of an electrical circuit, mechanical body, etc) having a tendency to self-oscillation
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for unstably
Online Etymology Dictionary, © 2010 Douglas Harper
- 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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.