semivocal

It would seem, then, that when one of these consonants follows a vowel, then sometimes the last note on the vowel sound is smoothly fused into the consonantal sound, part of its time value being given to the singing of the liquid or semivocal consonant.

The Catholic Encyclopedia, Volume 10: Mass Music-Newman 1840-1916 1913

A special modification of the neum form is that which is called liquescent or semivocal.

The Catholic Encyclopedia, Volume 10: Mass Music-Newman 1840-1916 1913

TH is either sibilant as in thigh; or semivocal as in thee; both of which are simple sounds, and want two new characters.

Note XV 1803

In speaking of articulate sounds they may be conveniently divided first into clear continued sounds, expressed by the letters called vowels; secondly, into hissing sounds, expressed by the letters, called sibilants; thirdly, into semivocal sounds, which consist of a mixture of the two former; and, lastly, into interrupted sounds, represented by the letters properly termed consonants.

Note XV 1803

I have preferred the word sonisibilants to the word semivocal sibilants; as the sounds of these sonisibilants are formed in different apertures of the mouth, and not in the larynx like the vowels.

Note XV 1803

The semivocal sounds are produced by the stream of air having received quick vibrations, or clear sound, in passing through the larynx, or in the cavity of the mouth; but

Note XV 1803

There are other clear sounds besides those formed by the larynx; some of them are formed in the mouth, as may be heard previous to the enunciation of the letters b, and d, and ga; or during the pronunciation of the semivocal letters, v.z. j. and others in sounding the liquid letters r and l; these sounds we shall term orisonance.

The Temple of Nature; or, the Origin of Society A Poem, with Philosophical Notes Erasmus Darwin 1766

I have preferred the word sonisibilants to the word semivocal sibilants; as the sounds of these sonisibilants are formed in different apertures of the mouth, and not in the larynx like the vowels.

The Temple of Nature; or, the Origin of Society A Poem, with Philosophical Notes Erasmus Darwin 1766

In speaking of articulate sounds they may be conveniently divided first into clear continued sounds, expressed by the letters called vowels; secondly, Into hissing sounds, expressed by the letters called sibilants; thirdly, Into semivocal sounds, which consist of a mixture of the two former; and, lastly, Into interrupted sounds, represented by the letters properly termed consonants.

The Temple of Nature; or, the Origin of Society A Poem, with Philosophical Notes Erasmus Darwin 1766

The semivocal sounds are produced by the stream of air having received quick vibrations, or clear sound, in passing through the larynx, or in the cavity of the mouth; but apart of it, as the outsides of this sonorous current of air, afterwards receives slower vibrations, or hissing sound, from some other passages of the lips or mouth, through which it then flows.

The Temple of Nature; or, the Origin of Society A Poem, with Philosophical Notes Erasmus Darwin 1766