A lateral is a consonant in which the airstream proceeds along the sides of the tongue, but it is blocked by the tongue from going through the middle of the mouth. An example of a lateral consonant is the English L, as in Larry.
For the most common laterals, the tip of the tongue makes contact with the upper teeth (see dental consonant) or the upper gum (see alveolar consonant), but there are many other possible places for laterals to be made. The most common laterals are approximants and belong to the class of liquids, but lateral fricatives and affricates are also common in some parts of the world. Some languages, such as the Iwaidja and Ilgar languages of Australia, have lateral flaps, and others, such as the Xhosa and Zulu languages of Africa, have lateral clicks.
When pronouncing the labiodental fricatives [f] and [v], the lip blocks the airflow in the centre of the vocal tract, so the airstream proceeds along the sides instead. Nevertheless, they are not considered lateral consonants because the airflow never goes over the tongue. No known language makes a distinction between lateral and non-lateral labiodentals. Plosives are never lateral, but they may have lateral release. Nasals are never lateral either, but some languages have lateral nasal clicks. For consonants articulated in the throat (laryngeals), the lateral distinction is not made by any language, although pharyngeal and epiglottal laterals are reportedly possible.
English has one lateral phoneme: the lateral approximant /l/, which in many accents has two allophones. One, found before vowels as in lady or fly, is called clear l, pronounced as the alveolar lateral approximant [l] with a "neutral" position of the body of the tongue. The other variant, so-called dark l, found before consonants or word-finally, as in bold or tell, is pronounced as the velarized alveolar lateral approximant [?] with the tongue assuming a spoon-like shape with its back part raised, which gives the sound a [w]- or [?]-like resonance. In some languages, like Albanian, those two sounds are different phonemes. East Slavic languages contrast [?] and [l?] but do not have [l].
In many British accents (e.g. Cockney), dark [?] may undergo vocalization through the reduction and loss of contact between the tip of the tongue and the alveolar ridge, becoming a rounded back vowel or glide. This process turns tell into something like [t], as must have happened with talk [t?:k] or walk [w?:k] at some stage. A similar process happened during the development of many other languages, including Brazilian Portuguese, Old French, and Polish, in all three of these resulting in voiced velar approximant [?] or voiced labio-velar approximant [w], whence Modern French sauce as compared with Spanish salsa, or Polish Wis?a (pronounced [viswa]) as compared with English Vistula.
In central and Venice dialects of Venetian, intervocalic /l/ has turned into a semivocalic [e?], so that the written word ?a ba?a is pronounced [abae?a]. The orthography uses the letter ? to represent this phoneme (it specifically represents not the [e?] sound but the phoneme that is, in some dialects, [e?] and, in others, [l]).
Many aboriginal Australian languages have a series of three or four lateral approximants, as do various dialects of Irish. Rarer lateral consonants include the retroflex laterals that can be found in many languages of India and in some Swedish dialects, and the voiceless alveolar lateral fricative /?/, found in many Native North American languages, Welsh and Zulu. In Adyghe and some Athabaskan languages like Hän, both voiceless and voiced alveolar lateral fricatives occur, but there is no approximant. Many of these languages also have lateral affricates. Some languages have palatal or velar voiceless lateral fricatives or affricates, such as Dahalo and Zulu, but the IPA has no symbols for such sounds. However, appropriate symbols are easy to make by adding a lateral-fricative belt to the symbol for the corresponding lateral approximant (see below). Also, a devoicing diacritic may be added to the approximant.
Nearly all languages with such lateral obstruents also have the approximant. However, there are a number of exceptions, many of them located in the Pacific Northwest area of the United States. For example, Tlingit has /t?, t, t?', ?, ?'/ but no /l/.[a] Other examples from the same area include Nuu-chah-nulth and Kutenai, and elsewhere, Chukchi and Kabardian.
Lateral trills are also possible, but they do not occur in any known language. They may be pronounced by initiating [?] or [?] with an especially forceful airflow. There is no symbol for them in the IPA. They are sometimes used to imitate bird calls, and they are a component of Donald Duck talk.
Only the alveolar lateral fricatives have dedicated letters in the IPA. However, others appear in the extIPA.
The IPA requires sounds to be defined as to centrality, as either central or lateral. However, languages may be ambiguous as to some consonants' laterality. A well-known example is the liquid consonant in Japanese, represented in common transliteration systems as ⟨r⟩, which can be recognized as a (post)alveolar tap,alveolar lateral flap, (post)alveolar lateral approximant, (post)alveolar approximant,voiced retroflex stop, and various less common forms.
A superscript ⟨?⟩ is defined as lateral release.
Consonants may also be pronounced with simultaneous lateral and central airflow. This is well-known from speech pathology with a lateral lisp. However, it also occurs in nondisordered speech in some southern Arabic dialects and possibly some Modern South Arabian languages, which have pharyngealized nonsibilant // and // (simultaneous [?] and [ð]) and possibly a sibilant /?/ (simultaneous [s]). Examples are /aim/ 'pain' in the dialect of Al-Rubu'ah and /ðahr/ 'back' and /ðab?/ 'hyena' in Rijal Alma'. (Here the ⟨?⟩ indicates simultaneous laterality rather than lateral release.) Old Arabic has been analyzed as having the emphatic central-lateral fricatives [?], [ð] and [?].