Fornax Syllabification: (For·nax)Pronunciation: /ˈfôrˌnaks/ AstronomyDefinition of Fornax an inconspicuous southern constellation (the Furnace), near Eridanus. (as genitive Fornacis /fôrˈnāsis/) used with a preceding letter or numeral to designate a star in this constellation:the star Beta FornacisOrigin:LatinFornax in other Oxford dictionaries Definition of Fornax in the British & World English dictionary