/ ˌɪnstəˈbɪləti; NAmE / noun [ U , C , usually pl. ] ( pl. -ies )
1.
the quality of a situation in which things are likely to change or fail suddenly :
political and economic instability
2.
a mental condition in which sb's behaviour is likely to change suddenly :
mental / emotional instability
OPP stability
—see also unstable
••
WORD ORIGIN
late Middle English : from French instabilité , from Latin instabilitas , from instabilis , from in- not + stabilis (from the base of stare to stand).