unstable: Meaning and Definition of

un•sta•ble

1. not stable; not firm or firmly fixed; unsteady.
2. liable to fall or sway.
3. unsteadfast; inconstant; wavering: unstable convictions.
4. marked by emotional instability: an unstable person.
5. irregular in movement: an unstable heartbeat.
6. noting compounds that readily decompose or change into other compounds.