Mesidor or Messidor: How To spell?
The word Mesidor is misspelled against Messidor, a noun meaning "The tenth month of the French republican calendar dating from September 22, 1792. It began June 19, and ended July 18. See VendEmiaire."
Messidor has double "ss" is mispronounced as "s"Remember double 'SS' in between the strings me & idor which should not be misspelled with single 'S'
Wrong Spelling:  me-s-idor  Correct Spelling:  me-ss-idor 
Find more incorrect spellings of Messidor to spell right way.