The Lonsdale Hundred is a historic hundred of Lancashire, England. Although named after the dale or valley of the River Lune, which runs through the city of Lancaster, for centuries it covered most of the north-western part of Lancashire around Morecambe Bay, including the detached parts of Furness and the Cartmel Peninsula. Ironically, only some of the detached part of North Lonsdale still remains partly within a British parliamentary constituency under the name of Lonsdale, being part of the Westmorland and Lonsdale constituency.