thallophytePronunciation: /ˈθalə(ʊ)fʌɪt/Definition of thallophyte noun Botany a plant that consists of a thallus. Origin: mid 19th century: from modern Latin Thallophyta (former taxon), from Greek thallos (see thallus) + -phytethallophyte in other Oxford dictionaries Definition of thallophyte in the US English dictionary