Unstable
Pronunciation : Un*sta"ble
Part of Speech : a.
Etymology : [Cf. Instable.]
Definition : Defn: Not stable; not firm, fixed, or constant; subject to change or overthrow. -- Un*sta"ble*ness, n. Chaucer. Unstable equilibrium. See Stable equilibrium, under Stable.
Source : Webster's Unabridged Dictionary, 1913