The word "aureating" means to give a golden or rich yellow color to something. Its antonyms would be words that describe the opposite effect. These antonyms might include words such as bleaching, whitening, paling, and fading. All of these words describe a process of lightening or removing color from an object, which is the opposite effect of "aureating." Other possible antonyms might include tarnishing, rusting, or corroding, since these words imply a process of decay or degradation rather than enhancement. Ultimately, the antonym for "aureating" depends on the context and the intended meaning of the word.