Apical consonant in the context of "Thorn (letter)"

A retroflex (/ˈrɛtrəflɛks, -roʊ-/ ) or cacuminal (/kəˈkjuːmɪnəl/ ) consonant is a coronal consonant where the tongue has a flat, concave, or even curled shape, and is articulated between the alveolar ridge and the hard palate. They are sometimes referred to as cerebral consonants—especially in Indology.

The Latin-derived word retroflex means "bent back"; some retroflex consonants are pronounced with the tongue fully curled back so that articulation involves the underside of the tongue tip (subapical). These sounds are sometimes described as "true" retroflex consonants. However, retroflexes are commonly taken to include other consonants having a similar place of articulation without such extreme curling of the tongue; these may be articulated with the tongue tip (apical) or the tongue blade (laminal). When apical, they have been called apico-domal consonants.

Linguolabials or apicolabials are consonants articulated by placing the tongue tip or blade against the upper lip, which is drawn downward to meet the tongue. They represent one extreme of a coronal articulatory continuum which extends from linguolabial to subapical palatal places of articulation. Cross-linguistically, linguolabial consonants are very rare. They are found in a cluster of languages in Vanuatu, in the Kajoko dialect of Bijago in Guinea-Bissau, in Umotína (a recently extinct Bororoan language of Brazil), and as paralinguistic sounds elsewhere. They are also relatively common in disordered speech, and the diacritic is specifically provided for in the extensions to the IPA.

Linguolabial consonants are transcribed in the International Phonetic Alphabet by adding the "seagull" diacritic, U+033C ◌̼ COMBINING SEAGULL BELOW, to the corresponding alveolar or dental consonant. Pullum & Ladusaw (1996) additionally suggest these sound may be equivalently transcribed with the apical diacritic, U+033A ◌̺ COMBINING INVERTED BRIDGE BELOW, on the corresponding bilabial consonant. However, Olson et al. (2009:64) reject this transcription, as linguolabials may be articulated either apical or laminal. The labial consonants ⟨p᫥, m̼, v̼⟩ have also been used. The choice of the base consonant may depend on whether the author analyses the linguolabial as being phonologically labial or alveolar.

A laminal consonant is a phone (speech sound) produced by obstructing the air passage with the blade of the tongue, the flat top front surface just behind the tip of the tongue, in contact with upper lip, teeth, alveolar ridge, to possibly, as far back as the hard palate, although in the last contact may involve parts behind the blade as well. It is distinct from an apical consonant, produced by creating an obstruction with the tongue apex (tongue tip) only. Laminal is sometimes used exclusively for an articulation that involves only the blade of the tongue with the tip being lowered and apicolaminal for an articulation that involves both the blade of the tongue and the raised tongue tip. The distinction applies only to coronal consonants, which use the front of the tongue.

Alveolar consonants (/ælˈviːələr/ ; UK also /ælviˈoʊlər/) are articulated with the tongue against or close to the superior alveolar ridge, which is called that because it contains the alveoli (the sockets) of the upper teeth. Alveolar consonants may be articulated with the tip of the tongue (the apical consonants), as in English, or with the flat of the tongue just above the tip (the "blade" of the tongue; called laminal consonants), as in French and Spanish.

The International Phonetic Alphabet (IPA) does not have separate symbols for the alveolar consonants. Rather, the same symbol is used for all coronal places of articulation that are not palatalized like English palato-alveolar sh, or retroflex. To disambiguate, the bridge ([s̪, t̪, n̪, l̪], etc.) may be used for a dental consonant, or the under-bar ([s̠, t̠, n̠, l̠], etc.) may be used for the postalveolars. [s̪] differs from dental [θ] in that the former is a sibilant and the latter is not. [s̠] differs from postalveolar [ʃ] in being unpalatalized.