dewlap

noun2

1. •
   The pendulous skin under the neck of an ox, or a similar feature on any other animal.

   • Fire burst from its open mouth, its eyes glowed with a smouldering glare, its muzzle and hackles and dewlap were outlined in flickering flame. — 1901
2. •
   The sagging flesh on the throat of an elderly human.

   • He ended up looking at himself in the mirror. His image stared back at him. He was developing a dewlap - a definite dewlap. He waggled under his chin scornfully with his fingers. — 2017