What does 'pucker' mean in terms of lips?

The term 'pucker' in relation to lips refers to the action of gathering the lips into small folds or wrinkles. This can happen naturally when someone is making a facial expression, like when they are about to kiss, are surprised, or are experiencing a sudden strong emotion. The process of puckering involves tightening and contracting the muscles around the lips, leading to that specific wrinkled appearance.

This understanding of 'pucker' is commonly recognized in both everyday language and more specialized contexts, such as cosmetics or expressions in acting. It encapsulates the idea of forming a crease or wrinkle, which is integral to the definition. The other options do not relate to this specific action, as they describe entirely different processes or meanings.