Approximant
Approximants are speech sounds that could be regarded as intermediate between
vowels and typical
consonants. In the articulation of approximants, articulatory organs produce a narrowing of the vocal tract, but leave enough space for air to flow without audible turbulence -- approximants are therefore more open than
fricatives. This class of sounds includes l-like
lateral approximants (e.g. different variants of English [l]), several r-like
rhotic sounds (e.g. [r\\'] as in
red), and so-called
semivowels, like [j] or [w] as in English
yes and
well.
Palatal semivowels correspond to front vowels, velar semivowels to back vowels, and labialized semivowels to rounded vowels. They are typically briefer, less stable and often closer than the corresponding vowels.