double chin
US /ˌdʌb.əl ˈtʃɪn/
UK /ˌdʌb.əl ˈtʃɪn/

1.
a fold of flesh under the chin, especially one caused by fat
:
•
He developed a double chin as he gained weight.
•
She tried exercises to reduce her double chin.
a fold of flesh under the chin, especially one caused by fat