Hefty means heavy, large, or substantial in size, weight, or amount. When you pick up a hefty textbook, you feel its weight pulling down on your arms. A hefty sandwich is thick and filling, packed with layers of meat, cheese, and vegetables. A hefty price tag means something costs a lot of money.

The word captures both physical weight and metaphorical size or importance. A hefty fine for breaking a rule is large enough to make you think twice. A hefty assignment might take several hours to complete. When a coach gives someone a hefty responsibility, like being team captain, it means the job involves real work and importance.

Hefty often suggests something bigger or heavier than you might expect. A hefty donation to charity is a generous amount that makes a real difference. You might describe someone as hefty when they're large and solid in build. The word has a sturdy, substantial feeling to it, like the difference between a flimsy plastic bag and a hefty canvas tote that can carry a stack of library books without tearing.