(Med.) n. an exceptionally virulent hemorrhaic virus with a high mortality rate, first recognized in an outbreak on the Ebola river in africa. [ PJC ]

n. (Med.) any of several dozen DNA-containing virus of the family Herpetoviridae, including among them such human-disease-causing agents as Herpes simplex virus causing oral and genital herpes, varicella-zoster virus (Herpes zoster virus) causing shingles and chickenpox (varicella), Epstein-Barr virus (EB virus) causing infectious mononucleosis, and Cytomegalovirus. [ PJC ]

n. (Med.) same as varicella-zoster virus. [ PJC ]

n. The virus that causes rubella. [ PJC ]

{ } n. [ Cf. F. virulence, L. virulentia an offensive odor, a stench. ] 1. The quality or state of being virulent or venomous; poisonousness; malignancy. [ 1913 Webster ]

2. Extreme bitterness or malignity of disposition. “Refuted without satirical virulency.” Barrow. [ 1913 Webster ]

The virulence of one declaimer, or the profundities and sublimities of the other. I. Taylor. [ 1913 Webster ]

a. [ L. virulentus, fr. virus poison: cf. F. virulent. See Virus. ] 1. Extremely poisonous or venomous; very active in doing injury. [ 1913 Webster ]

A contagious disorder rendered more virulent by uncleanness. Sir W. Scott. [ 1913 Webster ]

2. Very bitter in enmity; actuated by a desire to injure; malignant; as, a virulent invective. [ 1913 Webster ]

a. Made virulent; poisoned. [ Obs. ] [ 1913 Webster ]

adv. In a virulent manner. [ 1913 Webster ]

n. [ L., a slimy liquid, a poisonous liquid, poison, stench; akin to Gr. &unr_; poison, Skr. visha. Cf. Wizen, v. i. ] 1. (Med.) Contagious or poisonous matter, as of specific ulcers, the bite of snakes, etc.; -- applied to organic poisons. [ Archaic ] [ 1913 Webster +PJC ]

2. the causative agent of a disease, . [ obsolescent ] [ PJC ]

3. any of numerous submicroscopic complex organic objects which have genetic material and may be considered as living organisms but have no proper cell membrane, and thus cannot by themselves perform metabolic processes, requiring entry into a host cell in order to multiply. The simplest viruses have no lipid envelope and may be considered as complex aggregates of molecules, sometimes only a nucleic acid (DNA or RNA) and a coat protein. They are sometimes viewed as being on the borderline between living and nonliving objects. They are smaller than living cells in size, usually between 20 and 300 nm; thus they pass through standard filters, and were previously referred to as filterable virus. The manifestations of disease caused by multiplication of viruses in cells may be due to destruction of the cells caused by subversion of the cellular metabolic processes by the virus, or by synthesis of a virus-specific toxin. Viruses may infect animals, plants, or microorganisms; those infecting bacteria are also called bacteriophages. Certain bacteriophages may be non-destructive and benign in the host; -- see bacteriophage. [ 1913 Webster +PJC ]

4. Fig.: Any morbid corrupting quality in intellectual or moral conditions; something that poisons the mind or the soul; as, the virus of obscene books. [ 1913 Webster ]

5. (Computers) a program or segment of program code that may make copies of itself (replicate), attach itself to other programs, and perform unwanted actions within a computer; also called computer virus or virus program. Such programs are almost always introduced into a computer without the knowledge or assent of its owner, and are often malicious, causing destructive actions such as erasing data on disk, but sometime only annoying, causing peculiar objects to appear on the display. The form of sociopathic mental disease that causes a programmer to write such a program has not yet been given a name. Compare trojan horse{ 3 }. [ PJC ]