In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the vocal tract. Examples are and [b], pronounced with the lips; and [d], pronounced with the front of the tongue; and [g], pronounced with the back of the tongue; , pronounced in the throat; , [v], and , pronounced by forcing air through a narrow channel (fricatives); and and , which have air flowing through the nose (nasals). Contrasting with consonants are vowels.
Since the number of speech sounds in the world's languages is much greater than the number of letters in any one alphabet, linguists have devised systems such as the International Phonetic Alphabet (IPA) to assign a unique and unambiguous symbol to each attested consonant. The English alphabet has fewer consonant letters than the English language has consonant sounds, so digraphs like , , , and are used to extend the alphabet, though some letters and digraphs represent more than one consonant. For example, the sound spelled in "this" is a different consonant from the sound in "thin". (In the IPA, these are and , respectively.)
Etymology
The word consonant comes from Latin oblique stem , from 'sounding-together', a calque of Greek (plural , ).
Dionysius Thrax calls consonants ( 'sounded with') because in Greek they can only be pronounced with a vowel. He divides them into two subcategories: ( 'half-sounded'), which are the continuants, and ( 'unsounded'), which correspond to plosives.
This description does not apply to some languages, such as the Salishan languages, in which plosives may occur without vowels (see Nuxalk), and the modern concept of 'consonant' does not require co-occurrence with a vowel.
Consonant sounds and consonant letters
The word consonant may be used ambiguously for both speech sounds and the letters of the alphabet used to write them. In English, these letters are B, C, D, F, G, J, K, L, M, N, P, Q, S, T, V, X, Z and often H, R, W, Y.
In English orthography, the letters H, R, W, Y and the digraph GH are used for both consonants and vowels. For instance, the letter Y stands for the consonant/semi-vowel in yoke, the vowel in myth, the vowel in funny, the diphthong in sky, and forms several digraphs for other diphthongs, such as say, boy, key. Similarly, R commonly indicates or modifies a vowel in non-rhotic accents.
This article is concerned with consonant sounds, however they are written.
Consonants versus vowels
Consonants and vowels correspond to distinct parts of a syllable: The most sonorous part of the syllable (that is, the part that is easiest to sing), called the syllabic peak or nucleus, is typically a vowel, while the less sonorous margins (called the onset and coda) are typically consonants. Such syllables may be abbreviated CV, V, and CVC, where C stands for consonant and V stands for vowel. This can be argued to be the only pattern found in most of the world's languages, and perhaps the primary pattern in all of them. However, the distinction between consonant and vowel is not always clear cut: there are syllabic consonants and non-syllabic vowels in many of the world's languages.
One blurry area is in segments variously called semivowels, semiconsonants, or glides. On one side, there are vowel-like segments that are not in themselves syllabic, but form diphthongs as part of the syllable nucleus, as the i in English boil . On the other, there are approximants that behave like consonants in forming onsets, but are articulated very much like vowels, as the y in English yes . Some phonologists model these as both being the underlying vowel , so that the English word bit would phonemically be , beet would be , and yield would be phonemically . Likewise, foot would be , food would be , wood would be , and wooed would be . However, there is a (perhaps allophonic) difference in articulation between these segments, with the in yes and yield and the of wooed having more constriction and a more definite place of articulation than the in boil or bit or the of foot.
The other problematic area is that of syllabic consonants, segments articulated as consonants but occupying the nucleus of a syllable. This may be the case for words such as church in rhotic dialects of English, although phoneticians differ in whether they consider this to be a syllabic consonant, , or a rhotic vowel, : Some distinguish an approximant that corresponds to a vowel , for rural as or ; others see these as a single phoneme, .