approximanten

Approximants are a class of consonantal sounds produced with a relatively open vocal tract: the articulators approach each other but do not create the turbulent airflow characteristic of fricatives or the complete closure of stops. Because the vocal tract remains fairly open, approximants are typically sonorants and voiced, though some languages have voiceless variants.

The most familiar approximants are the semivowels or glides, such as the palatal approximant [j] (as in yes) and the labio-velar approximant [w] (as in we). Other common approximants include the liquids: the lateral approximant [l] and the rhotic approximant [ɹ] (which in many dialects is realized as [ɻ] or other rhotic shapes). In addition to these, languages may have a range of other articulations classified as approximants, such as [ɰ] (a velar or labial-velar approximant) and various alveolar, palatal, or retroflex articulants.

In phonological analyses, approximants are often grouped with vowels as sonorants, and their behavior can resemble that of vowels in some contexts (for example, glide-like articulations in onset positions). They commonly function as onsets in syllables and participate in a wide range of phonotactic patterns across languages. Some languages contrast voiced and voiceless approximants, or contrast different lengths or degrees of constriction, while others realize voiceless variants only as allophones conditioned by surrounding sounds.

See also: semivowels, vowels, rhotics, liquids.