Delude is from Latin deludere ('to mock, deceive'), from de- ('down, to one's detriment') + ludere ('to play'), from ludus ('game, play'). The ancestry passes through Latin deludere, Latin ludere, and Latin ludus. The prefix de- often marks removal, reversal, or downward motion in Latin formations, helping to explain the word's surface structure. In present use as a verb, it means "to mislead the mind or judgment of; deceive", keeping the historical formation close to the word's ordinary semantic work. Related words include delusion, delusive, elude, and illusion; derived forms include deluder, deluded, and deluding.