Dissuade is from Latin dissuadere ('to advise against'), from dis- ('against') + suadere ('to urge, advise, recommend'), related to suavis ('sweet, agreeable'). The ancestry passes through Latin dissuadere and Latin suadere. The prefix dis- often marks separation, reversal, or negation in Latin and English formations, helping to explain the word's surface structure. In present use as a verb, it means "to persuade someone not to take a course of action", keeping the historical formation close to the word's ordinary semantic work. Related words include persuade, suasion, and dissuasion; derived forms include dissuasion, dissuasive, dissuader, and dissuadable.