1. (v. i.) Contagious or poisonous matter, as of specific ulcers, the bite of snakes, etc.; -- applied to organic poisons.

2. (n.) The special contagion, inappreciable to the senses and acting in exceedingly minute quantities, by which a disease is introduced into the organism and maintained there.

3. (v. i.) Fig.: Any morbid corrupting quality in intellectual or moral conditions; something that poisons the mind or the soul; as, the virus of obscene books.

acaricide adenovirus aerial infection aerobe aerobic bacteria aerobic organism airborne infection amoeba anaerobe anaerobic bacteria anaerobic organism anthelmintic antibiotic antiseptic autotrophic organism bacillus bacteria bacterium bane being bug bug bomb carbamate insecticide carrier chemosterilant chlorinated hydrocarbon insecticide coccus communicability contact poison contagion contagiousness contamination corruption creature cryptogenic infection defoliant direct infection disease-producing microorganism disinfectant droplet infection dust infection echovirus enterovirus epidemiology eradicant filterable virus fumigant fungicide fungus genetic individual germ germicide gram-negative bacteria gram-positive bacteria hand infection herbicide heterotrophic organism indirect infection individual infection infectiousness insect powder insecticide living being living thing microbe microbicide microorganism miticide mold morphological individual nonfilterable virus ont organic being organic chlorine organic phosphate insecticide organism organization pathogen pesticide physiological individual phytogenic infection picornavirus poison primary infection protozoa protozoon pyogenic infection rat poison reovirus rhinovirus rickettsia roach paste roach powder rodenticide secondary infection spirillum spirochete spore staphylococcus stomach poison streptococcus subclinical infection systemic systemic insecticide taint toxic toxicant toxin trypanosome vector venin venom vermicide vibrio waterborne infection weed killer zoogenic infection zooid zoon