bundle [ME] Bundle may come from Old English byndelle ‘a binding’. In the mid 18th century anatomists and physiologists started using the Old English word ‘bundle’ for a set of muscle or nerve fibres running in parallel. The phrase a bundle of nerves is common in US sources from the 1880s. In horse racing bundle is a slang term for ‘a large sum of money’, first used in the US around 1880. If a person ‘goes a bundle on a horse’ they bet a lot of money on it.