The Collaborative International Dictionary of English v.0.48:

P \P\ (p[=e]),
   the sixteenth letter of the English alphabet, is a nonvocal
   consonant whose form and value come from the Latin, into
   which language the letter was brought, through the ancient
   Greek, from the Ph[oe]nician, its probable origin being
   Egyptian. Etymologically P is most closely related to b, f,
   and v; as hobble, hopple; father, paternal; recipient,
   receive. See B, F, and M.
   [1913 Webster] See Guide to Pronunciation, [sect][sect] 247,
   248, and 184-195.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Labial \La"bi*al\, n.
   1. (Phonetics) A letter or character representing an
      articulation or sound formed or uttered chiefly with the
      lips, as b, p, w.
      [1913 Webster]

   2. (Mus.) An organ pipe that is furnished with lips; a flue
      pipe.
      [1913 Webster]

   3. (Zool.) One of the scales which border the mouth of a fish
      or reptile.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Mute \Mute\, n.
   1. One who does not speak, whether from physical inability,
      unwillingness, or other cause. Specifically:
      (a) One who, from deafness, either congenital or from
          early life, is unable to use articulate language; a
          deaf-mute.
      (b) A person employed by undertakers at a funeral.
      (c) A person whose part in a play does not require him to
          speak.
      (d) Among the Turks, an officer or attendant who is
          selected for his place because he can not speak.
          [1913 Webster]

   2. (Phon.) A letter which represents no sound; a silent
      letter; also, a close articulation; an element of speech
      formed by a position of the mouth organs which stops the
      passage of the breath; as, p, b, d, k, t.
      [1913 Webster]

   3. (Mus.) A little utensil made of brass, ivory, or other
      material, so formed that it can be fixed in an erect
      position on the bridge of a violin, or similar instrument,
      in order to deaden or soften the tone.
      [1913 Webster]

WordNet (r) 3.0 (2006):

P
    n 1: a multivalent nonmetallic element of the nitrogen family
         that occurs commonly in inorganic phosphate rocks and as
         organic phosphates in all living cells; is highly reactive
         and occurs in several allotropic forms [syn: phosphorus,
         P, atomic number 15]
    2: the 16th letter of the Roman alphabet [syn: P, p]