'actinomycosis' originates from New Latin, specifically the word 'actinomyces,' where 'actino-' meant 'ray' and 'myces' meant 'fungus.'

'actinomyces' changed from the Greek word 'aktis' (ray) and 'mykes' (fungus) and eventually became the modern English word 'actinomycosis.'

Initially, it referred to a 'ray fungus,' but over time it evolved into its current meaning of a bacterial infection caused by Actinomyces species.