Source : Webster's Revised Unabridged Dictionary (1913)

Sore \Sore\, a. [Compar. {Sorer}; superl. {Sorest}.] [OE. sor,
   sar, AS. s[=a]r; akin to D. zeer, OS. & OHG. s?r, G. sehr
   very, Icel. s[=a]rr, Sw. s[*a]r, Goth. sair pain. Cf.
   {Sorry}.]
   1. Tender to the touch; susceptible of pain from pressure;
      inflamed; painful; -- said of the body or its parts; as, a
      sore hand.

   2. Fig.: Sensitive; tender; easily pained, grieved, or vexed;
      very susceptible of irritation.

            Malice and hatred are very fretting and vexatious,
            and apt to make our minds sore and uneasy.
                                                  --Tillotson.

   3. Severe; afflictive; distressing; as, a sore disease; sore
      evil or calamity. --Shak.

   4. Criminal; wrong; evil. [Obs.] --Shak.

   {Sore throat} (Med.), inflammation of the throat and tonsils;
      pharyngitis. See {Cynanche}.

   {Malignant}, {Ulcerated} or {Putrid}, {sore throat}. See
      {Angina}, and under {Putrid}.

Malignant \Ma*lig"nant\, n.
   1. A man of extrems enmity or evil intentions. --Hooker.

   2. (Eng. Hist.) One of the adherents of Charles L. or Charles
      LL.; -- so called by the opposite party.

Malignant \Ma*lig"nant\, a. [L. malignans, -antis, p. pr. of
   malignare, malignari, to do or make maliciously. See
   {Malign}, and cf. {Benignant}.]
   1. Disposed to do harm, inflict suffering, or cause distress;
      actuated by extreme malevolence or enmity; virulently
      inimical; bent on evil; malicious.

            A malignant and a turbaned Turk.      --Shak.

   2. Characterized or caused by evil intentions; pernicious.
      ``Malignant care.'' --Macaulay.

            Some malignant power upon my life.    --Shak.

            Something deleterious and malignant as his touch.
                                                  --Hawthorne.

   3. (Med.) Tending to produce death; threatening a fatal
      issue; virulent; as, malignant diphtheria.

   {Malignant pustule} (Med.), a very contagious disease,
      transmitted to man from animals, characterized by the
      formation, at the point of reception of the virus, of a
      vesicle or pustule which first enlarges and then breaks
      down into an unhealthy ulcer. It is marked by profound
      exhaustion and usually fatal. Called also {charbon}, and
      sometimes, improperly, {anthrax}.

Source : WordNet®

malignant
     adj 1: dangerous to health; characterized by progressive and
            uncontrolled growth (especially of a tumor) [ant: {benign}]
     2: extremely malevolent or malicious; "the malignant tongues of
        gossipers" [syn: {malevolent}]