Definition of Lip

Lip: One of the two fleshy folds which surround the opening of the mouth.

The upper lip is separated from the nose by the philtrum, the area that lies between the base of the nose and the pigmented edge (called the vermillion border or the carmine margin) of the upper lip.

The upper and lower lips meet at the corners (or angles) of the mouth which, in anatomy, are called the oral commissures. The oral commissure normally lies in a vertical line below the pupil.

Small blind pits are sometimes seen at the corners of the mouth; they are known as angular lip pits and are considered normal minor variants.

The lips may be abnormally thin or thick. For example, the upper lip is typically thin and the philtrum flat in children with the fetal alcohol syndrome. If the upper lip is overgrown, the corners of the mouth appear to be downturned.

The lips are not only features of anatomy. They are also organs of speech. A sound requiring the participation of one or both lips is referred to as a labial (labium in Latin means lip) sound. All labial sounds are consonants. There are bilabial sounds such as "p" which involve both lips and labiodental sounds such as "v" which involve the upper teeth and lower lip.

The word "lip" can be traced back to the Indo-European "leb" which also produced the Latin "labium" from which came the French "levre." The German "lippe" is just a slip from the English "lip." See also: Labrose.