Hey, you asked…
Vomitus is the stuff that you throw up from the stomach when you vomit. It usually contains food and some stomach acids that your body produces to help digest food (which explains why sometimes vomit burns your nose).
Vomiting can actually help protect you from serious injury or even death. If you eat or drink something that your body thinks is poisonous, your stomach sends a signal to your brain to get rid of it. These signals cause the muscles in your stomach to contract very hard and eject the vomitus from your stomach through your throat and out your mouth (and sometimes out of your nose for added effect). Things that your body might think is poisonous include alcohol, drugs, or even spoiled food. This explains why even though vomiting is not fun, you often feel better after you throw up.
If the vomitus is reddish color, then there might be a problem. It could be fresh or dried blood that indicates you are bleeding internally. Or it could be food coloring from the red soft drink you just drank.
Another word for vomiting is emesis.