Definition of unstable
- an unstable pulse
- an unstable tower
- an unstable economy
- unstable weather
an unstable nuclear reactor core
the minute we put the books down on the unstable desk, the whole stack went crashing to the floor
These example sentences are selected automatically from various online news sources to reflect current usage of the word 'unstable.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
capricious, changeable, changeful, fickle, flickery, fluctuating, fluid, inconsistent, inconstant, mercurial, mutable, skittish, temperamental, uncertain, unpredictable, unsettled, unsteady, variable, volatile;
up in the air;
: likely to change
: not emotionally or mentally healthy
: not held in a secure position : likely to move or fall
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