Answer: Euphemism
Explanation: Euphemism is a word that has a Greek root and means to replace some unpleasant or shameful word or expression with some milder, indirect expression or word. It is used instead of some harsh expression, most often, say, to replace the term dead, and so used passed away. However, sometimes it is not a good idea to use a euphemism to mitigate or mask the seriousness of the problem, such as when you say social drinker instead of alcoholic.
