loose [ME] The medieval word loose is related to Old English lose and loss, and also to the ending -less, signifying ‘without’. The sense ‘immoral, promiscuous’ dates from around 1470 from the original sense ‘free from bonds’. The term a loose cannon sounds as if it should be centuries old, perhaps from the days of warships in Napoleonic battles. In fact, the first recorded uses are from the late 19th century, and the phrase only really gained currency in the 1970s. That said, it does come from the idea that a cannon which has broken loose from its mounting would be a particularly dangerous hazard on any ship, but especially a wooden one. See also fast.