Wordnet 3.0
NOUN (1)
1.
tenth month of the Revolutionary calendar (June and July);
the month of harvest;
The Collaborative International Dictionary of English v.0.48:
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.
[1913 Webster]
WordNet (r) 3.0 (2006):
Messidor
n 1: tenth month of the Revolutionary calendar (June and July);
the month of harvest