band

Band comes from Middle English band (also bond), from Old English beand/bænd/bend, meaning a bond, chain, fetter, or ribbon, ultimately from Proto-Germanic *bandiz and Proto-Indo-European *bʰendʰ- ("to tie, bind"). A second stream flowed in through Old French bande, from Old Occitan banda ("regiment of troops"), possibly from a Frankish word for a tie, tracing back to the same Germanic and PIE roots.

One line of the word stuck close to its literal roots, meaning something physical that ties or binds — a strap, ribbon, or fetter. The other line drifted through military use, where 'banda' meant a regiment of troops bound together as a unit, a sense that eventually gave English the modern group-of-people meaning, as in a musical band.

It's a close cousin of bond and bind, both of which trace back to the same Proto-Indo-European root *bʰendʰ- meaning 'to tie.' German Bande, Dutch band, and Swedish band all carry the same ancient thread.