'bacterioprotein' originates from New Latin/Neo-Latin elements: the prefix 'bacterio-' (from Greek 'bakterion' meaning 'small rod') combined with 'protein' (from Greek 'proteios' meaning 'primary' via the 19th-century scientific coinage 'protein').

'bacterioprotein' was formed in Modern English by combining the element 'bacterio-' (ultimately from Greek 'bakterion' via New Latin 'bacterium') with the noun 'protein' (a 19th-century scientific term coined from Greek roots), creating a compound meaning a protein associated with bacteria.

Initially the roots referred separately to 'small rod' ('bacterio-') and 'primary' ('protein' originally from 'protos'); over time the compound came to mean simply 'a protein associated with bacteria' without preserving the literal senses of the separate roots.