slough [OE] A slough is a swamp (slōh in Old English), and a slough of despond a condition of despondency, hopelessness, and gloom. The phrase comes from John Bunyan’s The Pilgrim’s Progress (1678). Slump [L17th] originally meant to fall in a bog and probably came from the sound that would be made. The economic sense is late 19th century. The slough meaning the skin shed by a snake is Middle English and originally meant ‘skin’ in English. It may be related to Low German sluwe ‘husk, peel’.