Barron's TOEFL R-2

Adjective unable to bend or be forced out of shape
Armadillos have rigid shields over their shoulders and hips and additional armor that covers the top of their head, the upper parts of their limbs, and tail.
Adjective strong and healthy
Drinking games, late-night parties far from disapproving parents, and youthfully robust livers make for an intoxicating pastime that's tough to curtail.