'bacilluria' originates from New Latin/medical formation, combining the Latin noun 'bacillus' and the Greek-derived combining form '-uria' (from Greek 'ouron' meaning 'urine'), where 'bacillus' meant 'little rod' (diminutive of Latin 'baculum', 'stick').

'bacilluria' was formed in modern medical/Neo-Latin usage by joining 'bacillus' with the suffix '-uria' (used to denote conditions of the urine) and entered English in medical literature as a technical term for 'bacilli in the urine'.

Initially coined to denote literally 'bacilli in the urine', the term has retained that specific clinical meaning and is used primarily as a laboratory/clinical descriptor.