adjective

(of a quality) definite; unquestionable.

the sunshine is a decided improvement

distinct,clear,clear-cut,marked,pronounced,obvious,striking,noticeable,unmistakable,patent,manifest,express,definite,certain,positive,absolute,emphatic,categorical,unambiguous,undeniable,unequivocal,indisputable,undisputed,unquestionable,assured,guaranteed,sensible