More. A virus was originally the venom of a snake, and was an English borrowing of a Latin word meaning âslimy liquidâ or âpoisonâ, that is also the source of virulent (Late Middle English).Early medical practitioners used the word for a substance produced in the body as the result of disease.ore. A virus was originally the venom of a snake, and was an English borrowing of a Latin word meaning âslimy liquidâ or âpoisonâ, that is also the source of virulent (Late Middle English).