From Middle English bustlen, bustelen, bostlen, perhaps an alteration of *busklen (> Modern English buskle), a frequentative of Middle English busken (“to prepare; make ready”), from Old Norse búask (“to prepare oneself”); or alternatively from a frequentative form of Middle English busten, bisten (“to buffet; pummel; dash; beat”) + -le. Compare also Icelandic bustla (“to splash; bustle”).