labial

a.

  1. Of or pertaining to the lips or labia; as, labial veins.
  2. Furnished with lips; as, a labial organ pipe.
  3. Articulated, as a consonant, mainly by the lips, as b, p, m, w.
  4. Modified, as a vowel, by contraction of the lip opening, as / (f/d), / (/ld), etc., and as eu and u in French, and o, u in German. See Guide to Pronunciation, // 11, 178.
  5. Of or pertaining to the labium; as, the labial palpi of insects. See Labium.

n.

  1. A letter or character representing an articulation or sound formed or uttered chiefly with the lips, as b, p, w.
  2. An organ pipe that is furnished with lips; a flue pipe.
  3. One of the scales which border the mouth of a fish or reptile.