'bandog' originates from Middle English, specifically the word 'bandogge', where 'band' meant 'a chain or bond' and 'dog' meant 'dog'.

'bandog' changed from the Middle English word 'bandogge' and eventually became the modern English word 'bandog'.

Initially, it meant 'a dog kept on a chain (during the day) and let loose at night to guard,' but over time it evolved into the broader current meaning of 'any large or ferocious guard dog' and occasionally a figurative 'ferocious person'.