Not in a state of physical or conceptual equilibrium; lacking stability, fairness, or proper proportion between different elements or aspects.
From Old French 'balance' (scales, balance) with prefix 'un-' (not). The word evolved from describing physical scales to mental states, arguments, and any system where forces or elements are not in proper equilibrium.
Your inner ear contains tiny stones called otoliths that help you stay balanced - when they get displaced, you feel dizzy and unbalanced! Similarly, an unbalanced argument is missing the 'weight' on one side, like having stones only on one side of the scale.
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