WordWeb Online

1. Subject to change or variation
   "her unsteady walk"; "his hand was unsteady as he poured the wine"; "an unsteady voice"
    
2. Not firmly or solidly positioned
   "climbing carefully up the unsteady ladder"
   - unfirm

See also: aflicker, agitated, aquiver, arrhythmic, atremble, convulsive, faltering, flickering, fluctuating, irregular, jerking, jerky, palpitant, palpitating, quavering, shaky, shifting, shifty, shivering, shuddering, spasmodic, spastic, tottering, tottery, trembling, tremulous, uneven, unfixed, unstable, unsteadily, unsteadiness, wobbling

Antonym: steady