The word "colorant" refers to a substance that adds color to something. Antonyms for this word might include words like "bleach" or "whitener" which would describe a substance that removes color, rather than adds it. Other antonyms for "colorant" might be words that describe a lack of color or a neutral shade. For example, "transparent" or "clear" would indicate a substance that is colorless, while "gray" or "neutral" might describe something that has very little color or a balanced blend of different hues. Ultimately, the appropriate antonym for "colorant" will depend on the context in which the word is being used and the desired meaning of the sentence.