Speech disorder: A disorder affecting the ability to produce normal speech. Speech disorders may affect articulation (phonetic or phonological disorders); fluency (stuttering or cluttering); and/or voice (tone, pitch, volume, or speed). Most speech disorders have their roots in oral-motor differences, although some involve language processing problems. Diagnosis is by testing by a speech pathologist. Treatment is by speech therapy.

See also: Apraxia; Alogia; Aphasia; Articulation disorder.