Achernar Syllabification: (A·cher·nar)Pronunciation: /ˈakərˌnär, ˈäk-/ AstronomyDefinition of Achernar the ninth brightest star in the sky, and the brightest in the constellation Eridanus. It marks the southern limit of Eridanus, and is only visible to observers in the southern hemisphere. Origin:from Arabic, 'end of the river (i.e., Eridanus)'Achernar in other Oxford dictionaries Definition of Achernar in the British & World English dictionary