instability

(ĭn'stə-bĭl'ĭ-tē)
n., pl., -ties.

1. Lack of physical stability; unsteadiness.
2. The quality or condition of being erratic or undependable: emotional instability; political instability.

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noun

1. The quality or condition of being physically unsteady: precariousness, ricketiness, shakiness, unstableness, unsteadiness, wobbliness. See flexible/rigid.
2. The quality or condition of being erratic and undependable: insecureness, insecurity, precariousness, shakiness, unstableness, unsteadiness, unsureness. See change/persist, strong/weak.

n

Definition: imbalance, inconstancy
Antonyms: balance, constancy, soundness, stability, steadfastness

The condition of a parcel of air which has positive buoyancy, and thus a tendency to rise through the atmosphere. It is the temperature of the parcel relative to the ambient air which is critical, since this affects densities. A parcel remains unstable if it cools more slowly than the surrounding, stationary air. Absolute instability occurs when an air parcel, displaced vertically, is hastened in the direction of the displacement, and such a move will be checked when the temperature of the parcel is at one with its surroundings. The potential instability of a parcel of air can be calculated using a tephigram.

Conditional instability occurs when a parcel of air would become unstable if lifted by some other force. This can take place when a lower, stable parcel of air is overlain by an unstable layer. If any agency, such as a mountain, or the moistening of the lower-level air, can ‘nudge’ it upwards, it will become unstable. Convective instability is a tendency of an air parcel towards instability when it has been lifted bodily until completely saturated. This will often occur when it responds to the inevitable stirrings in the atmosphere.

The atmosphere is said to be unstable if the environmental lapse rate is greater than both the dry and saturated adiabatic lapse rates; that is, when the fall of temperature with height of the environmental air is more rapid than that experienced by a rising air parcel, so that the air parcel continues to be less dense than the ambient air.

In a structure, the sudden loss of stiffness that limits its load-carrying capability, and in some cases results in the structure’s failure.

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Lack of stability in a joint, often through lax ligaments associated with hyperflexibility. Joint instability predisposes an athlete to injuries such as recurrent dislocations.

i. A state of the atmosphere in which a parcel of air will continue to rise, if for any reason, it is pushed up. Any instability in the atmosphere means turbulent conditions exist. The environmental lapse rate (ELR) in this case will be higher than both dry and saturated adiabatic lapse rates. Dry adiabatic lapse rate (DALR) is the rate of decrease of temperature with height of a parcel of dry air lifted adiabatically. Its value is 3°/1000 ft. Saturated adiabatic lapse rate (SALR) is the lapse rate of a parcel of saturated air and its value is 1.5°/1000 ft.



ii. A tendency of a body to continue moving away from its original state when disturbed by an external force and to continue after that force has been withdrawn.
iii. The failure of structures, such as the buckling of plates and panels under compression, and the failure of struts under end loads.

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For a list of words related to instability, see:

• Agitation, Abnormality, and Instability - instability: tendency to behave in an unpredictable or erratic manner

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  See crossword solutions for the clue Instability.

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Dansk (Danish)
n. - usikkerhed, ustadighed, instabilitet

Nederlands (Dutch)
onevenwichtigheid, labiliteit, onvastheid

Français (French)
n. - instabilité, (Mécan) déséquilibrage, (Météo) instabilité, manque de solidité, mobilité, instabilité (de caractère)

Deutsch (German)
n. - Instabilität, Labilität

Ελληνική (Greek)
n. - αστάθεια, ρευστότητα

Italiano (Italian)
instabilità

Português (Portuguese)
n. - instabilidade (f)

Русский (Russian)
неустойчивость

Español (Spanish)
n. - inestabilidad, desequilibrio

Svenska (Swedish)
n. - instabilitet, obeständighet

中文（简体）(Chinese (Simplified))
不安定, 基础薄弱, 不稳定

中文（繁體）(Chinese (Traditional))
n. - 不安定, 基礎薄弱, 不穩定

한국어 (Korean)
n. - 불안정, 변하기 쉬움

日本語 (Japanese)
n. - 不安定, 不安定状態

العربيه (Arabic)
‏(الاسم) عدم استقرار‏

עברית (Hebrew)
n. - ‮חוסר יציבות, חוסר שיווי-משקל, אי-סדירות‬

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