unstable

To be unstable is to lack stability, meaning things could change without warning, like an unstable bookshelf that is likely to fall down. If you are unstable emotionally, you might be ecstatically happy one minute and horribly depressed and angry the next.

The adjective unstable means the opposite of stable. Stable is derived from the Latin base word stare meaning “to stand.” If a building, family, person, bridge, or chemical solution is stable it will “stand still,” even if something unexpected happens. On the other hand, if a person or thing is unstable and stress is applied, he, she, or it is likely to shift position, possibly in a dangerous way.

Definitions of unstable
1

adj subject to change; variable

“everything was unstable following the coup”
Synonyms:
fluid
changeable, changeful
such that alteration is possible; having a marked tendency to change

adj lacking stability or fixity or firmness

unstable political conditions”
“the tower proved to be unstable in the high wind”
“an unstable world economy”
Synonyms:
inconstant
likely to change frequently often without apparent or cogent reason; variable
impermanent, temporary
not permanent; not lasting
coseismal, coseismic
being where earthquake waves arrive simultaneously
crank, cranky, tender, tippy
(used of boats) inclined to heel over easily under sail
explosive, volatile
liable to lead to sudden change or violence
rickety, shaky, wobbly, wonky
inclined to shake as from weakness or defect
rocky
liable to rock
seismal, seismic
subject to or caused by an earthquake or earth vibration
top-heavy
unstable by being overloaded at the top
tottering
(of structures or institutions) having lost stability; failing or on the point of collapse
volcanic
explosively unstable
unsteady
subject to change or variation
Antonyms:
stable
resistant to change of position or condition
constant
steadfast in purpose or devotion or affection
lasting, permanent
continuing or enduring without marked change in status or condition or place
firm, steady, unfluctuating
not liable to fluctuate or especially to fall
lasting
lasting a long time without change
stabile
(chemistry, physics, biology) resistant to change
stabilised, stabilized
made stable or firm
steady
not subject to change or variation especially in behavior
show more antonyms...

adj affording no ease or reassurance

Synonyms:
precarious
uneasy
lacking a sense of security or affording no ease or reassurance

adj suffering from severe mental illness

Synonyms:
mentally ill, unsound
insane
afflicted with or characteristic of mental derangement

adj disposed to psychological variability

“his rather unstable religious convictions”
Synonyms:
irresolute
uncertain how to act or proceed

adj highly or violently reactive

“sensitive and highly unstable compounds”
Synonyms:
reactive
participating readily in reactions

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