(Originally) any morbid matter or morbific agent that is difficult to detect; (in later use) specifically any virus that infects a plant or animal without causing apparent disease.
Origin
Mid 18th century.
Definition of latent virus in US English:
latent virus
noun
(Originally) any morbid matter or morbific agent that is difficult to detect; (in later use) specifically any virus that infects a plant or animal without causing apparent disease.