adj. 25B6; adjective
icebergs are notoriously unstable : UNSTEADY, rocky, wobbly, rickety, shaky, unsafe, insecure, precarious.
unstable coffee prices : CHANGEABLE, volatile, variable, fluctuating, irregular, unpredictable, erratic.
he was mentally unstable : UNBALANCED, of unsound mind, mentally ill, deranged, demented, disturbed, unhinged.
steady, firm.