'infusoric' originates from New Latin, specifically the word 'Infusoria', where the element 'infus-' (from Latin 'infundere') meant 'to pour in' and the suffix '-oria' denoted 'things' or a collective.

'infusoric' developed in English in the 19th century as an adjective/noun formed from New Latin 'Infusoria' (used for microscopic organisms found in infusions) by adding the English adjectival suffix '-ic'.

Initially it referred specifically to organisms found in plant or other infusions; over time it remained a specialized, largely historical term for such microscopic aquatic organisms or descriptions relating to them.