'bandolier' originates from French, specifically the word 'bandoulière', ultimately from Spanish 'bandolera' (from 'banda' meaning 'sash' or 'band').

'bandoulière' (French) and Spanish 'bandolera' influenced English forms 'bandolier' and variant 'bandoleer'; the word entered English in the 16th–17th centuries and took the present spelling and usage.

Initially it meant 'a shoulder belt (for cartridges)'; over time it has retained that core meaning, with derived verbal/adjectival uses meaning 'provided with or wearing such a belt'.