1. (

• unstable

) lacking stability or fixity or firmness; "unstable political conditions"; "the tower proved to be unstable in the high wind"; "an unstable world economy" ;

2. (

• unstable

) highly or violently reactive; "sensitive and highly unstable compounds" ;

3. (

• precarious ,
• unstable

) affording no ease or reassurance; "a precarious truce" ;

4. (

• mentally_ill ,
• unsound ,
• unstable

) suffering from severe mental illness; "of unsound mind" ;

5. (

• unstable

) disposed to psychological variability; "his rather unstable religious convictions" ;

6. (

• fluid ,
• unstable

) subject to change; variable; "a fluid situation fraught with uncertainty"; "everything was unstable following the coup" ;