backerEnglishOxford English Thesaurusbacker noun 1 £3 million was provided by the project's backers: sponsor, investor, subsidizer, underwriter, promoter, financier, patron, benefactor, benefactress, guarantor, supporter, friend; informal angel; rare Maecenas. 2 the backers of the proposition: supporter, upholder, champion, defender, advocate, promoter, proponent, protagonist; seconder, second; North American booster.backer Oxford Dictionary of English