Source : Webster's Revised Unabridged Dictionary (1913)

Philter \Phil"ter\, n. [F. philtre, L. philtrum, Gr. ?, fr. ? to
   love, ? dear, loving.]
   A potion or charm intended to excite the passion of love.
   [Written also {philtre}.] --Addison.

Source : WordNet®

philtre
     n : a drink credited with magical power; can make the one who
         takes it love the one who gave it [syn: {philter}, {love-potion},
          {love-philter}, {love-philtre}]