Rationibus is a Latin word that means "by reason." When people use this term, they usually mean that they are doing something because it makes sense or has good reasons behind it. For example, if you ask your mom why you have to eat vegetables, she might say, "It's rationibus – because they help you grow strong and healthy!" Rationibus is like having a good answer or explanation that your brain agrees with. It helps you understand why something is happening or why you should do something. So, the next time someone uses the word rationibus, you'll know they're talking about a smart idea that makes sense!