The Collaborative International Dictionary of English v.0.48:

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.
      [1913 Webster]

            A malignant and a turbaned Turk.      --Shak.
      [1913 Webster]

   2. Characterized or caused by evil intentions; pernicious.
      "Malignant care." --Macaulay.
      [1913 Webster]

            Some malignant power upon my life.    --Shak.
      [1913 Webster]

            Something deleterious and malignant as his touch.
                                                  --Hawthorne.
      [1913 Webster]

   3. (Med.) Tending to produce death; threatening a fatal
      issue; virulent; as, malignant diphtheria.
      [1913 Webster]

   Malignant pustule (Med.), a very contagious disease
      produced by infection of subcutaneous tissues with the
      bacterium Bacillus anthracis. It is transmitted to man
      from animals and is characterized by the formation, at the
      point of reception of the infection, of a vesicle or
      pustule which first enlarges and then breaks down into an
      unhealthy ulcer. It is marked by profound exhaustion and
      often fatal. The disease in animals is called charbon;
      in man it is called cutaneous anthrax, and formerly was
      sometimes called simply anthrax.
      [1913 Webster +PJC]

The Collaborative International Dictionary of English v.0.48:

Anthrax \An"thrax\ ([a^]n"thr[a^]ks), n. [L., fr. Gr. 'a`nqrax
   coal, carbuncle.]
   1. (Med.)
      (a) A carbuncle.
      (b) A malignant pustule.
          [1913 Webster]

   2. (Biol.) A microscopic, bacterial organism (Bacillus
      anthracis), resembling transparent rods. [See Illust.
      under Bacillus.]
      [1913 Webster]

   3. An infectious disease of cattle and sheep. It is ascribed
      to the presence of a rod-shaped gram-positive bacterium
      (Bacillus anthracis), the spores of which constitute the
      contagious matter. It may be transmitted to man by
      inoculation. The spleen becomes greatly enlarged and
      filled with bacteria. Called also splenic fever.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Carbuncle \Car"bun*cle\, n. [L. carbunculus a little coal, a
   bright kind of precious stone, a kind of tumor, dim. of carbo
   coal: cf. F. carboncle. See Carbon.]
   [1913 Webster]
   1. (Min.) A beautiful gem of a deep red color (with a mixture
      of scarlet) called by the Greeks anthrax; found in the
      East Indies. When held up to the sun, it loses its deep
      tinge, and becomes of the color of burning coal. The name
      belongs for the most part to ruby sapphire, though it has
      been also given to red spinel and garnet.
      [1913 Webster]

   2. (Med.) A very painful acute local inflammation of the
      subcutaneous tissue, esp. of the trunk or back of the
      neck, characterized by brawny hardness of the affected
      parts, sloughing of the skin and deeper tissues, and
      marked constitutional depression. It differs from a boil
      in size, tendency to spread, and the absence of a central
      core, and is frequently fatal. It is also called
      anthrax.
      [1913 Webster]

   3. (Her.) A charge or bearing supposed to represent the
      precious stone. It has eight scepters or staves radiating
      from a common center. Called also escarbuncle.
      [1913 Webster]

WordNet (r) 3.0 (2006):

anthrax
    n 1: a highly infectious animal disease (especially cattle and
         sheep); it can be transmitted to people [syn: anthrax,
         splenic fever]
    2: a disease of humans that is not communicable; caused by
       infection with Bacillus anthracis followed by septicemia

Moby Thesaurus II by Grady Ward, 1.0:

189 Moby Thesaurus words for "anthrax":
   African lethargy, Asiatic cholera, Chagres fever, German measles,
   Haverhill fever, Minamata disease, Texas fever,
   acute articular rheumatism, ague, alkali disease,
   altitude sickness, amebiasis, amebic dysentery, anoxemia, anoxia,
   anoxic anoxia, aphthous fever, bacillary dysentery,
   bastard measles, bighead, black death, black fever, black lung,
   black quarter, blackleg, blackwater, blackwater fever,
   blind staggers, bloody flux, breakbone fever, broken wind,
   brucellosis, bubonic plague, cachectic fever, caisson disease,
   cattle plague, cerebral rheumatism, charbon, chicken pox,
   chilblain, cholera, cowpox, dandy fever, decompression sickness,
   deer fly fever, dengue, dengue fever, diphtheria, distemper,
   dumdum fever, dysentery, elephantiasis, encephalitis lethargica,
   enteric fever, erysipelas, famine fever, five-day fever, flu,
   foot-and-mouth disease, frambesia, frostbite, gapes, glanders,
   glandular fever, grippe, hansenosis, heaves, hepatitis, herpes,
   herpes simplex, herpes zoster, histoplasmosis, hog cholera,
   hoof-and-mouth disease, hookworm, hydrophobia, immersion foot,
   infantile paralysis, infectious mononucleosis,
   inflammatory rheumatism, influenza, itai, jail fever, jet lag,
   jungle rot, kala azar, kissing disease, lead poisoning, lepra,
   leprosy, leptospirosis, liver rot, loa loa, loaiasis, lockjaw,
   loco, loco disease, locoism, mad staggers, madness, malaria,
   malarial fever, malignant catarrh, malignant catarrhal fever,
   malignant pustule, mange, marsh fever, measles, megrims,
   meningitis, mercury poisoning, milzbrand, motion sickness, mumps,
   ornithosis, osteomyelitis, paratuberculosis, paratyphoid fever,
   parotitis, parrot fever, pertussis, pip, pneumoconiosis, pneumonia,
   polio, poliomyelitis, polyarthritis rheumatism, ponos,
   pseudotuberculosis, psittacosis, quarter evil, rabbit fever,
   rabies, radiation sickness, radionecrosis, rat-bite fever, red-out,
   relapsing fever, rheumatic fever, rickettsialpox, rinderpest,
   ringworm, rot, rubella, rubeola, scabies, scarlatina,
   scarlet fever, schistosomiasis, septic sore throat, sheep rot,
   shingles, sleeping sickness, sleepy sickness, smallpox,
   snail fever, splenic fever, spotted fever, staggers, strep throat,
   stringhalt, sunstroke, swamp fever, swine dysentery, tetanus,
   the bends, thrush, tinea, trench fever, trench foot, trench mouth,
   tuberculosis, tularemia, typhoid, typhoid fever, typhus,
   typhus fever, undulant fever, vaccinia, varicella, variola,
   venereal disease, viral dysentery, whooping cough, yaws,
   yellow fever, yellow jack, zona, zoster