'bacteriotoxin' originates from a combination of the combining form 'bacterio-' (from Greek 'bakterion' meaning 'small staff, rod') and the noun 'toxin' (from Greek 'toxikon' meaning 'poison').

'bacterio-' was incorporated into New Latin and scientific vocabulary (as in 'bacterium'), while 'toxin' entered English via modern scientific Latin/Greek; the two elements were combined in modern scientific English to form the compound 'bacteriotoxin'.

Initially the elements referred separately to a 'rod-shaped microbe' and to 'poison'; over time the compound came to mean specifically 'a poison produced by bacteria'.