The quality or state of being confidential; the degree to which something is meant to be kept secret.
From confidential (Latin confidentia, 'trust') + -ness suffix forming abstract nouns. The root confide means 'to trust' and evolved through Old French and Late Latin from Latin confidere.
This word appeared frequently in legal and diplomatic documents starting in the 1700s, reflecting how societies developed formal rules about secrets as trust became economically important—you couldn't have banking or contracts without protecting sensitive information.
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