a.
1.
Smooth, glib.
2.
Unstable, uncertain, changeable, mutable, unsteady, shaky, insecure, perilous, unsafe.
3.
Treacherous, perfidious, faithless, knavish, dishonest, false, cunning, shifty, elusive.
4.
Wanton, incontinent, unchaste, false, unfaithful.