The word "achromatous" refers to something that is without color or lacking in pigmentation. Therefore, antonyms for this word would be words that describe things that have color, vibrancy, or pigment. Some possible antonyms include colorful, vivid, bright, lively, and vibrant. Other antonyms could include chromatic, polychromatic, varicolored, and multicolored. All of these words evoke feelings of life, energy, and vibrancy, offering a sharp contrast to the dull, lifeless connotations of "achromatous." By using these antonyms in your writing, you can create a sense of joy, liveliness, and enthusiasm in your writing, making it more engaging and memorable for your readers.