adj. amounting to, as good as, virtually the same as, (pretty) much the same as, equal to, equivalent to, like, of a piece with, comparable to, commensurate with His response, for all its politeness, was tantamount to a rejection
TANTAMOUNT TO
Meaning of TANTAMOUNT TO in English
Oxford thesaurus English vocab. Английский словарь Оксфорд тезаурус. 2012