'autoinfection' originates from Greek and Latin, specifically Greek 'autos' where 'auto-' meant 'self', and Latin 'infectio' (from 'inficere') where 'inficere' meant 'to taint or infect'.

'autoinfection' was formed in modern medical English by combining the Greek prefix 'auto-' with the Latin-derived English word 'infection' (from Late Latin 'infectio'), producing the compound term used in parasitology and clinical medicine.

Initially, the components meant 'self' and 'infection/taint'; the combined term originally meant 'self-contamination or reinfection' and has remained focused on infections originating within the same host, becoming more specialized in parasitology and clinical usage over time.