Source : Webster's Revised Unabridged Dictionary (1913)

Obnoxious \Ob*nox"ious\ ([o^]b*n[o^]k"sh[u^]s), a. [L. obnoxius;
   ob (see {Ob-}) + noxius hurtful. See {Noxious}.]
   1. Subject; liable; exposed; answerable; amenable; -- with
      to.

            The writings of lawyers, which are tied obnoxious to
            their particular laws.                --Bacon.

            Esteeming it more honorable to live on the public
            than to be obnoxious to any private purse. --Milton.

            Obnoxious, first or last, To basest things --Milton.

   2. Liable to censure; exposed to punishment; reprehensible;
      blameworthy. ``The contrived and interested schemes of . .
      . obnoxious authors.'' --Bp. Fell.

            All are obnoxious, and this faulty land, Like
            fainting Hester, does before you stand Watching your
            scepter.                              --Waller.

   3. Offensive; odious; hateful; as, an obnoxious statesman; a
      minister obnoxious to the Whigs. --Burke. --
      {Ob*nox"ious*ly}, adv. -- {Ob*nox"ious*ness}, n. --South.

Source : WordNet®

obnoxious
     adj : causing disapproval or protest; "a vulgar and objectionable
           person" [syn: {objectionable}, {unpleasant}]