When you denigrate someone or something, you talk in a way that makes them seem smaller, worse, or less worth respect. You are not only saying “I disagree.” You are trying to pull them down in other people’s eyes. People denigrate a person’s work, their ideas, their background, or even a whole group. It is a fairly formal word: you will meet it in news, essays, and careful argument more than in playground talk. A friend would more likely say “they’re talking you down” or “they’re being really mean about it.” Though actually, the old picture behind the word is “to blacken” — as if you were rubbing a stain onto someone’s name. That is why it feels harsher than a fair complaint. You will often hear it in warnings: “Don’t denigrate what you don’t understand.”