Source : Webster's Revised Unabridged Dictionary (1913)

Pluviose \Plu`vi`[^o]se"\, n. [F. See {Pluvious}.]
   The fifth month of the French republican calendar adopted in
   1793. It began January 20, and ended February 18. See
   {Vend['e]miaire}.

Source : WordNet®

Pluviose
     n : fifth month of the Revolutionary calendar (January and
         February); the rainy month