Okay kiddo, do you know what an acid is? It's a substance that can give away a hydrogen ion when it's in water. Anhydride is a word we use to describe a chemical that doesn't have water in it. Now, when we put these two words together, it means a type of chemical that's made when two acids are combined without any water left over.
Let me give you an example that might help you understand better. Do you remember baking cookies? We use flour and sugar to make them, right? Now, if we want to make a different kind of cookie, we might mix flour and sugar with butter instead of water. The butter helps them stick together and form a new substance. This is kind of like what happens when we combine two acids without water and make an acid anhydride.
Sometimes acid anhydrides can be dangerous because they can react with water in your body and make acid. That's why it's important to be careful when working with them. But scientists and engineers use acid anhydrides to make all sorts of things, like plastics, medicines, and even flavorings for our food. So, while they might sound a little scary, acid anhydrides are actually pretty cool!