from The Century Dictionary.

  • The tenth letter in the English alphabet.
  • As a numeral, a variant form of I: used chiefly at the end of a series of numerals, and now only in medical prescriptions: as, vj (six); viij (eight).
  • In mathematics, -j stands for the second unit vector or other unit of a multiple algebra. J usually denotes the Jacobian.
  • In thermodynamics, J is the mechanical equivalent of heat (being the initial of Joule).
  • See function.


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