To nauseate means to make someone feel sick to their stomach, like they might throw up. A disgusting smell can nauseate you. Watching someone eat something revolting might nauseate you. Even spinning around too fast on a playground merry-go-round can nauseate you until you have to sit down and wait for the world to stop spinning.

When something nauseates you, it triggers that awful feeling of nausea, that queasy, uncomfortable sensation in your stomach when you think you might vomit. A long car ride on winding roads might nauseate passengers who get carsick. The smell of spoiled milk nauseates most people instantly.

People also use nauseate to describe something so unpleasant or offensive that it makes them feel disgusted, even if they don't literally feel sick. You might say that someone's cruel behavior nauseates you, meaning it's so wrong that it makes you feel almost physically ill with disgust.

Be careful not to confuse nauseate with nauseous. When something nauseates you, it makes you feel sick. You then feel nauseated. Many people say “I feel nauseous,” but “I feel nauseated” is another way to say it. Something that causes that feeling is nauseating.