MessidorPronunciation: /ˈmɛsɪdɔː, mɛsidɔʀ/Definition of Messidor noun the tenth month of the French Republican calendar (1793–1805), originally running from 19 June to 18 July. Origin:French, from Latin messis 'harvest' + Greek dōron 'gift'Messidor in other Oxford dictionaries Definition of Messidor in the US English dictionary