• Louis Pasteur used the term "virus" (Latin for venom or poisonous fluid) to describe unknown infectious agents that could not be seen under a microscope but caused diseases like rabies.

• Although Martinus Beijerinck (1898) is often credited in modern textbooks for coining the term in its current biological sense (referring specifically to the filterable pathogen), historical records and many standard academic sources attribute the initial naming/usage of the term meaning "venom" to Pasteur.

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