Curled lip is a facial expression that indicates contempt or disgust. Antonyms for curled lip would be expressions that convey positive emotions. These could include a smile, which represents happiness, joy, and contentment. Another antonym could be a calm expression, indicating relaxation or serenity. A neutral expression, such as a straight face, could also be considered an antonym for curled lip, representing a lack of emotion or neutrality. In essence, antonyms for curled lip are any expressions that do not signal contempt or disgust, and instead convey positive, calm, or neutral emotions.