or NTH PLUS ONE, subs. (university).—See quot.

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  1864.  BREWER, Dictionary of Phrase and Fable, s.v. … NTH, to the utmost degree. Thus Cut to the Nth means wholly unnoticed by a friend. The expression is taken from the index of a mathematical formula, where n stands for any number, and n plus 1 more than any number.

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