​WATERLOO-WITH-SEAFORTH, an urban district in the Bootle and Ormskirk parhamentary divisions of Lancashire, England, at the mouth of the Mersey, 4 m. N. by W. of Liverpool. Pop. (1891) 17,225; (1901) 23,102. On account of its facilities for bathing, firm sands, pleasant scenery and nearness to Liverpool, of which it is a suburb, it is much frequented both by visitors and by residents.