instable
adjective
in·sta·ble (ˌ)in-ˈstā-bəl 
: unstable
Example Sentences
Recent Examples on the Web Photo: agencja gazeta/Reuters Some commentators compared the murder to the killing of Jo Cox, a British liberal legislator who was shot and stabbed to death by a mentally instable man inspired by far-right politics. 
Bojan Pancevski, WSJ, 14 Jan. 2019 With today's instable geopolitical times, a theatrical reboot offers fresh fodder for the show to put a mirror up to society. Ben Panko, Smithsonian, 19 July 2017
Bojan Pancevski, WSJ, 14 Jan. 2019 With today's instable geopolitical times, a theatrical reboot offers fresh fodder for the show to put a mirror up to society. Ben Panko, Smithsonian, 19 July 2017 Word History
Etymology
Middle English, from Middle French or Latin; Middle French, from Latin instabilis, from in- + stabilis stable
First Known Use
15th century, in the meaning defined above