• WordNet 3.6
    • adj unstable subject to change; variable "a fluid situation fraught with uncertainty","everything was unstable following the coup"
    • adj unstable affording no ease or reassurance "a precarious truce"
    • adj unstable highly or violently reactive "sensitive and highly unstable compounds"
    • adj unstable disposed to psychological variability "his rather unstable religious convictions"
    • adj unstable suffering from severe mental illness "of unsound mind"
    • adj unstable lacking stability or fixity or firmness "unstable political conditions","the tower proved to be unstable in the high wind","an unstable world economy"
    • ***
Webster's Revised Unabridged Dictionary
  • Interesting fact: The Leaning Tower of Pisa was built on the site of a river estuary. The land under the town has several layers of silt and soft clay. The 15,000-ton tower tilts to the south because the subsoil is too unstable.
    • a Unstable Not stable; not firm, fixed, or constant; subject to change or overthrow.
    • ***
Chambers's Twentieth Century Dictionary
    • adj Unstable un-stā′bl not stable, unreliable, infirm, inconstant: in such a physical state that the slightest change induces further change of form or composition
    • ***


  • Charles Caleb Colton
    “Honor is unstable and seldom the same; for she feeds upon opinion, and is as fickle as her food.”


Webster's Revised Unabridged Dictionary
Cf. Instable


In literature:

Such other salts which are decomposed more or less readily are termed "unstable," but the terms are of course only comparative.
"The Chemistry of Hat Manufacturing" by Watson Smith
But it had been taken at the expense of further and very gravely shaking the already unstable armed equilibrium of Europe.
"A General Sketch of the European War" by Hilaire Belloc
As I was saying, it is very unstable.
"The Good Comrade" by Una L. Silberrad
He had built a dream-house on an unstable foundation.
"The Hidden Places" by Bertrand W. Sinclair
My Lords, human greatness is an unstable thing.
"The Works of the Right Honourable Edmund Burke, Vol. X. (of 12)" by Edmund Burke
Peace not bought by a victory is an unstable foundation for Indian treaty.
"Pathfinders of the West" by A. C. Laut
No doubt it is between the stable and the unstable condition of the molecules of matter that life is born.
"The Breath of Life" by John Burroughs
The arc is very unstable and the least breath is sufficient to extinguish it.
"Scientific American Supplement, No. 315, January 14, 1882" by Various
Really unstable slopes had been shaken down long ago.
"Operation: Outer Space" by William Fitzgerald Jenkins
The Homoean coalition was even more unstable than the Eusebian.
"The Arian Controversy" by H. M. Gwatkin

In poetry:

O restless heart and fevered brain,
Unquiet and unstable,
That holy well of Loch Maree
Is more than idle fable!
"The Well of Loch Maree" by John Greenleaf Whittier
I could not among the misty clouds
Your unstable and painful image catch,
"Oh, my God", I promptly said aloud,
Having not a thought these words to fetch.
""I could not among the misty clouds"" by Osip Emilevich Mandelstam
I’ve not seen some sadder than your rabble,
And such black as all your lakes and streams,
In your skies – old, faded and unstable –
Yellow clouds of my painful dreams.
"You're Again With Me" by Innokentii Fedorovich Annensky
If Love so lived and ran and slept and woke
And ran in beauty when each morning broke,
Love yet was boylike, fervid and unstable,
Teased with romance, not knowing truth from fable.
"I Have Never Loved You Yet" by John Freeman
Side by side with Lady Mabel
Sate I, with the sunshade down;
In the distance hummed the Babel
Of the many—footed town;
There we sate with looks unstable—
Now of tenderness, of frown.
"Lady Mabel" by Alfred Austin
These earthly visions prove, alas! unstable;
And we are all too prone to clutch them fast,
Though false, aye, falser than the veriest fable,
To which a "thread of gossamer is cable—"
They cannot—cannot last!
"The Surviving Thought" by David James Scott

In news:

Friday's mass killing of young innocents and adults at a Connecticut elementary school is generating fresh calls for new laws to keep guns from unstable people.
The news is reporting layoffs, bailouts, and an unstable world market.
Authorities say gas leaks and unstable buildings have made them too risky to visit.
Cole, 57, was charged after calling a Denver radio talk show last October and revealing how she pretended to be mentally unstable to avoid her civic obligation.
The coffee market has been an unstable landscape since crop damage in Brazil sent prices through the roof this summer.
Good evening… A member of the Afghan militia drugged nine of his colleagues before shooting them to death early Friday in the latest outbreak of violence in the unstable country.
St Vincent, fashions an unstable compound of wistful synths, jittery rhythms, and woozy voices as the mood escalates from serenity to hysteria on this unsettling track.
At times, the New York Stock Exchange can be quite unstable.
Today's workplace is a reflection of the times: uncertain and unstable.
Wednesday morning, the State Police reported that an apparently mentally unstable woman threatened to blow up the State House.
Unstable dam reported near Traverse City .
For all its reputation as the world's most unstable region, the Middle East has actually been extremely stable in one respect — almost all of its states are ruled by dictators who tend to rule for decades.
The unstable weather southern oregon has seen recently Is forecast to continue for the next two weeks .
But what was acceptable in Paris would not pass in the more politically unstable atmosphere of Naples.
Unstable Euro Triggers 2011 Price Increases.

In science:

Our interest is to describe the time evolution of the unstable state |1i, which is an even function in coordinate representation.
Perturbative method for generalized spectral decompositions
Let us consider the time evolution of the unstable state given by (ρ0 | = (1|.
Perturbative method for generalized spectral decompositions
For example, it is possible to obtain the time evolution of the unstable state ρ0 = (1|.
Perturbative method for generalized spectral decompositions
Using a centered approximation for these terms results in an unstable scheme.
Simple excision of a black hole in 3+1 numerical relativity
However, as discussed at the end of this section, an unstable mode appears when the same simulations are performed on the corresponding full grids.
Simple excision of a black hole in 3+1 numerical relativity