Human face, with left nasolabial fold marked in black ellipse
The nasolabial folds, commonly known as "smile lines" or "laugh lines", are facial features. They are the two skin folds that run from each side of the nose to the corners of the mouth. They separate the cheeks from the upper lip. The term derives from Latinnasus for "nose" and labium for "lip".
With ageing the fold may become more pronounced and may be become cosmetically undesirable to some. Others may consider it a sign of maturity, age, or character. The most significant factors that contribute to the prominence of the fold are excess skin, skin thinning, excess cheek fat, and ptosis of cheek fat.