Any speech sound characterized by an articulation in which a closure or narrowing of the vocal tract completely or partially blocks the flow of air; also, any letter or symbol representing such a sound.
Consonants are usually classified according to the place of articulation (e.g., palate, teeth, lips); the manner of articulation, as in stops (complete closure of the oral passage, released with a burst of air), fricatives (forcing of breath through a constricted passage), and trills (vibration of the tip of the tongue or the uvula); and the presence or absence of voicing, nasalization, aspiration, and other features.