资料来源 : Webster's Revised Unabridged Dictionary (1913)

Messidor \Mes`si`dor"\ (F. ?; E. ?), n. [F., fr. L. messis
   harvest.]
   The tenth month of the French republican calendar dating from
   September 22, 1792. It began June 19, and ended July 18. See
   {Vend['E]miaire}.

资料来源 : WordNet®

Messidor
     n : tenth month of the Revolutionary calendar (June and July);
         the month of harvest