Messier, Charles Syllabification: (Mes·sier, Charles)Pronunciation: /ˈmesēˌā, mesˈyā/Definition of Messier, Charles (1730–1817), French astronomer. He discovered a number of nebulae, galaxies, and star clusters, which he designated by M numbers. Messier, Charles in other Oxford dictionaries Definition of Messier, Charles in the British & World English dictionary