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late 15c., in Scottish dreg-boat "boat for dredging," perhaps ultimately from root of drag (possibly via Middle Dutch dregghe "drag-net"). The verb is attested from c.1500 in Scottish. Related: Dredged; dredging.
To find or discover by effort and persistence: Let's dredge up more dirt on the candidate (1950s+)
(Job 24:6). See CORN.
large floating device for underwater excavation. Dredging has four principal objectives: (1) to develop and maintain greater depths than naturally exist for canals, rivers, and harbours; (2) to obtain fill to raise the level of lowlands and thus create new land areas and improve drainage and sanitation; (3) to construct dams, dikes, and other control works for streams and seashore; and (4) to recover subaqueous deposits or marine life having commercial value