From Longman Dictionary of Contemporary Englishunstableun‧sta‧ble /ʌnˈsteɪbəl/ ●○○ AWL adjective 1 CHANGE/BECOME DIFFERENTlikely to change suddenly and become worse → instability The political situation is still very unstable. an unstable relationship2 BALANCE#something that is unstable is likely to move or fall3 CHANGE/BECOME DIFFERENTsomeone who is unstable changes very suddenly so that you do not know how they will react or behave a mentally unstable man4 HCan unstable chemical is likely to separate into simpler substances
Examples from the Corpus
unstable• The situation here is precarious, quite unstable.• The situation there remains very unstable.• This moves their orbital electrons from the ground state to a higher energy level that is unstable.• Regimes governed by violence are always unstable.• Was it safe to trust someone who was so emotionally unstable?• Handy rejects a full-blown version of this vision on the grounds that such a divergent society would be very unstable.• It was potentially extremely dangerous and although it had survived since the war it may have been very unstable.• He is emotionally unstable, and his aggressive attitude often culminates in violence.• The isotope U-235 is unstable, decaying by a process called spontaneous fission.• an unstable economy• That scaffolding looks unstable - get all the building workers off the site immediately.• Mentally unstable, he would kill his parents in an explosive night of violence.• The woman, who was described as mentally unstable, refused to talk about her reasons for the shooting.• Working with Clare every day, I began to realize how unstable she was. 