FomalhautPronunciation: /ˈfəʊm(ə)lˌhɔːt, -məˌləʊt/ AstronomyDefinition of Fomalhaut the brightest star in the constellation Piscis Austrinus. Origin:Arabic, 'mouth of the fish'Fomalhaut in other Oxford dictionaries Definition of Fomalhaut in the US English dictionary