The term "au naturel" refers to a state or condition that is in its natural form. The antonyms for this term include artificial, unnatural, man-made, synthetic, and altered. These words describe something that has been changed or modified from its original state. Artificial refers to something that is made by humans rather than occurring naturally. Unnatural suggests something that is not in accordance with nature or the laws of nature. Man-made refers to something that is created by people. Synthetic describes something that is produced by chemical or mechanical means. Altered refers to something that has been changed from its original state. Overall, these antonyms of "au naturel" imply a lack of authenticity and a departure from the natural state.