Shockingly unfair, unjust, or unreasonable; going against conscience and basic human decency.
From the prefix 'un-' (not) combined with 'conscience' (from Latin 'conscientia' meaning 'knowledge of right and wrong'). The suffix '-able' makes it an adjective meaning 'not having conscience.'
A lawyer might say a contract is 'unconscionable' if it's so unfair that no reasonable person with a conscience would agree to it—it's one of the strongest words courts use to reject completely unjust deals!
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