1) Not stable 2) Unstable 
• (a.) Not stable; not standing fast or firm; unstable; prone to change or recede from a purpose; mutable; inconstant.
In·sta'ble adjective [ Latin instabilis : confer French instable . See In- not, and Stable , adjective , and confer Unstable .] Not stable; not standing fast or firm; unstable; prone to change or recede from a purpose; mutable; inconstant. 
not stable; unstable.