adjective.
Not firm, solid, or securely in place; unstable.
adjective.
Fluctuating; changeable.
adjective.
Not even or regular; wavering.
transitive verb.
To cause to become unsteady.
The Century Dictionary and Cyclopedia
Not steady.
In mech., having a motion which is not uniform or which does not take place with a constant angular velocity, or around a permanent axis through the center of gravity of the mass. Revolving bodies out of running balance have an unsteady motion.