spirant

When the lips are not tightly closed the sound produced is not a stop, but a spirant like the English w.

Spirant, spī′rant, n. a consonant which is fricative or continuable—opp.

Spirant, v like the ou in French oui, but later approximating to the w heard in some parts of Germany, Ed.

In twien b 210 from twiga the spirant has disappeared, as in monie b 168.