Fiend (noun) refers to a person who is extremely enthusiastic or obsessed with something, often in a way that seems almost fanatical; it can also mean a cruel or wicked person. In slang, fiend can describe someone who is relentlessly pursuing something, such as a “workout fiend” or “video-game fiend.” Historically, it also carried connotations of a demon or malevolent spirit in some contexts. The term combines menace with intensity, but is commonly used in modern speech with a more neutral or humorous tone depending on context.
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