Source : Webster's Revised Unabridged Dictionary (1913)

Antilogarithm \An`ti*log"a*rithm\, n. (Math.)
   The number corresponding to a logarithm. The word has been
   sometimes, though rarely, used to denote the complement of a
   given logarithm; also the logarithmic cosine corresponding to
   a given logarithmic sine. -- {An`ti*log`a*rith"mic}, a.