The first letters of a person's first and last names, or to sign with one's initials.
From Latin 'initiālis' (of beginning), from 'initium' (beginning). The practice of using initials to sign documents dates back centuries in formal writing.
Using initials to sign documents is a centuries-old practice that shows how shorthand can convey authority—your initials are legally binding in a way your full name sometimes isn't, which seems backwards but reveals how formality works.
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