The Collaborative International Dictionary
Labialize \La"bi*al*ize\, v. t. (Phonetics) To modify by contraction of the lip opening.
Wiktionary
vb. (context transitive English) To round, make (a sound, notably a consonant) labial.
WordNet
Usage examples of "labialize".
As noted above, some combinations should apparently be thought of as single consonants: qu (for cw/kw) represents labialized k, not k + w.
Probably w merged with the g or k preceding it: The combinations gw, kw are evidently best taken as unitary sounds, labialized versions of g and k (that is, g or k pronounced with poised lips look up Lesson One again).
In Quenya, which possessed besides the _calmatéma_ both a palatal series (_tyelpetéma_) and labialized series (_quessetéma_), the palatals were represented by a Fëanorian diacritic denoting 'following _y_' (usually two underposed dots), while Series IV was a _kw_-series.
In Quenya, which possessed besides the calmatéma both a palatal series (tyelpetéma) and labialized series (quessetéma), the palatals were represented by a Fëanorian diacritic denoting 'following y' (usually two underposed dots), while Series IV was a kw-series.
The digraphs in -w represent labialized consonants, while the digraphs in -y stand for palatalized consonants.
The question of length: It may seem that when they occur medially between vowels, the palatalized and labialized consonants count as long or double consonants (as if the digraphs represented actual consonant clusters after all).