means The state of being unsteady, easily disrupted, or prone to change, whether in physical structures, situations, emotions, or systems.

from From Latin 'instabilitas,' built from 'in-' (not) plus 'stabilis' (steady, firm) — which itself grows from 'stare,' to stand. So at its root the word means literally 'unable to stand,' a cousin of 'stable,' 'establish,' and 'stance.' It reached English through French in the 1400s, carrying that same image of something that simply won't keep its feet.