Source : Webster's Revised Unabridged Dictionary (1913)

Impertinent \Im*per"ti*nent\, a. [F., fr. L. impertinens,
   -entis; pref. im- not + pertinens. See {Pertinent}.]
   1. Not pertinent; not pertaining to the matter in hand;
      having no bearing on the subject; not to the point;
      irrelevant; inapplicable.

            Things that are impertinent to us.    --Tillotson.

            How impertinent that grief was which served no end!
                                                  --Jer. Taylor.

   2. Contrary to, or offending against, the rules of propriety
      or good breeding; guilty of, or prone to, rude,
      unbecoming, or uncivil words or actions; as, an impertient
      coxcomb; an impertient remark.

   3. Trifing; inattentive; frivolous.

   Syn: Rude; officious; intrusive; saucy; unmannerly;
        meddlesome; disrespectful; impudent; insolent.

   Usage: {Impertinent}, {Officious}, {Rude}. A person is
          officious who obtrudes his offices or assistance where
          they are not needed; he is impertinent when he
          intermeddles in things with which he has no concern.
          The former shows a want of tact, the latter a want of
          breeding, or, more commonly, a spirit of sheer
          impudence. A person is rude when he violates the
          proprieties of social life either from ignorance or
          wantonness. ``An impertinent man will ask questions
          for the mere grafication of curiosity; a rude man will
          burst into the room of another, or push against his
          person, inviolant of all decorum; one who is officious
          is quite as unfortunate as he is troublesome; when he
          strives to serve, he has the misfortune to annoy.''
          --Crabb. See {Impudence}, and {Insolent}.

Impertinent \Im*per"ti*nent\, n.
   An impertinent person. [R.]

Source : WordNet®

impertinent
     adj 1: characterized by a lightly pert and exuberant quality; "a
            certain irreverent gaiety and ease of manner" [syn: {irreverent},
             {pert}, {saucy}]
     2: not pertinent to the matter under consideration; "an issue
        extraneous to the debate"; "the price was immaterial";
        "mentioned several impertinent facts before finally coming
        to the point" [syn: {extraneous}, {immaterial}, {orthogonal}]
     3: improperly forward or bold; "don't be fresh with me";
        "impertinent of a child to lecture a grownup"; "an
        impudent boy given to insulting strangers" [syn: {fresh},
        {impudent}, {overbold}, {smart}, {saucy}, {sassy}]