'bandog' originates from Middle English, specifically the word 'bandogge', where 'band' meant 'fetter, chain' (a binding) and 'dog' meant 'dog'.

'bandog' changed from Middle English 'bandogge' (also seen as 'bandog') and developed into the modern English 'bandog' via Early Modern English usage.

Initially, it meant 'a dog kept on a band (chain) for guarding', but over time it evolved into the broader modern sense of 'a large fierce guard dog' (the chained implication is often lost in general usage).