Why is Data with an Overrepresented Class called Imbalanced not Unbalanced?

Question

I've seen the term Imbalanced used to described data that has an over-representation of one class.

What's the reasoning behind naming this type of data Imbalanced as opposed to Unbalanced, which seems to fit the intended meaning perfectly already?

Answer 1

Unbalanced:

not balanced: such as
a: not in equilibrium
b: mentally disordered : affected with mental illness
c: not adjusted so as to make credits equal to debits
an unbalanced account

Imbalanced:

lack of balance : the state of being out of equilibrium or out of proportion
a structural imbalance
a chemical imbalance in the brain

Imbalanced is used when something is out of proportion, Unbalanced when you can destabilise something. Although Imbalanced may sometimes be more correct or the only correct word to use, I rarely see it used outside of academic circles, datasciences or similar areas.