Heavy, strong, vigorous, mighty, impressive.
He can throw a hefty punch.
Strong; bulky.
They use some hefty bolts to hold up road signs.
(of a person) Possessing physical strength and weight; rugged and powerful; powerfully or heavily built.
He was a tall, hefty man.
Heavy, weighing a lot.
She carries a hefty backpack full of books.
(of a number or amount) Large.
That's going to cost you a hefty sum.