The term "curling lip" typically refers to a negative facial expression indicating disgust, contempt, or disdain. However, there are several antonyms that describe positive expressions of the lips.
The first is "smiling." A smile is a gentle upward curve of the lips, indicating happiness, kindness, or friendliness.
Another antonym is "pouting." A pout is a slight protrusion of the lips, indicating sadness, frustration, or disappointment.
A third antonym is "puckering." Puckering is the act of forming small wrinkles or creases around the lips, indicating a kiss, affection, or playfulness.
Overall, while "curling lip" describes a negative expression, there are many positive antonyms that can be used to describe different facial expressions.