Rational means based on clear thinking and logic rather than on emotions or wild guesses. A rational decision is one you make by carefully considering the facts and thinking through the likely outcomes.

When your friend wants to buy the first puppy she sees without asking about its needs or whether her family can care for it, she's acting emotionally. When she instead researches different breeds, considers her family's schedule and space, and thinks about the long-term responsibility, she's being rational. She's using her head to make a thoughtful choice.

In math and science, rational has a more specific meaning. A rational number is any number you can write as a fraction, like 3/4 or 7/2. The number 0.5 is rational because it equals 1/2. Even whole numbers like 5 are rational since you could write them as 5/1. Numbers that can't be written as fractions, like pi or the square root of 2, are called irrational numbers.

Being rational doesn't mean ignoring your feelings completely. It means using clear thinking to guide your choices. When you're upset that you didn't make the soccer team, a rational response might be to practice more and try again next year rather than quitting sports altogether or blaming the coach. Rational thinking helps you see situations clearly and respond in ways that actually help.