Weight is the measure of how heavy something is, or how strongly gravity pulls on it. When you step on a scale, it shows your weight. When you lift a backpack full of books, you feel its weight pulling down on your arms.

Weight depends on both mass (the amount of matter in something) and gravity. A bowling ball has more mass than a basketball, so it has more weight. But here's something amazing: if you took that same bowling ball to the moon, it would weigh only one-sixth as much as it does on Earth, because the moon's gravity is weaker. The bowling ball itself hasn't changed, but the force pulling on it has.

The word also describes importance or influence. A teacher might give more weight to your test scores than to your homework when calculating grades. When someone's opinion carries weight, people take it seriously. A Supreme Court decision carries weight because it affects millions of people.

You can also describe something as weighty when it's physically heavy or seriously important. A weighty textbook is hard to carry, but a weighty decision is one that requires careful thought because it matters so much. When someone says a problem is weighing on them, they mean it feels heavy in their mind, like a burden they're carrying.