A speech disorder characterized by a lack of normal fluency.

A person who stutters repeats words and parts of words, prolongs sounds, has difficulty producing sounds (usually at the beginning of words or groups of words), and generally speaks in fragmented phrases. ("Stuttering" and "stammering" are synonymous. The former is used more frequently in the United States, while the latter is the preferred term in Britain.) Due to the frustration and embarrassment caused by this problem, stuttering is usually accompanied by anxiety about speaking. It is estimated that stuttering affects about one percent of the general population in the world's industrialized nations—2.5 million people in the United States alone. It is much more common in males than females: the ratio is generally thought to be about four to one (and according to some estimates may even be as high as nine to one). About four-fifths of children who...