In simple word, we can say that make someone unsteady so that they fall is called unbalance.
In theoretical language, the condition which exists in a rotor when vibratory force or motion is imparted to its bearings as a result of centrifugal forces is called unbalance or the uneven distribution of mass about rotor's rotating line.
In theoretical language, the condition which exists in a rotor when vibratory force or motion is imparted to its bearings as a result of centrifugal forces is called unbalance or the uneven distribution of mass about rotor's rotating line.