This word looks a little like tomato, but you don't grow hematomas in the garden! Hematoma is just a medical word for bruise, or black and blue mark. The "hema" part of the word means blood, which is what you see under your skin if you get a bad bump. When you get a bad bump, the blood vessels break and the blood leaks out. But then your body goes to work to clean things up. Before you know it, the black and blue color has faded to green or yellow and then it's all gone.