chinstrap

noun3

1. •
   A strip of leather or material used to fasten a hat or helmet under the chin.

   • A bridle, the chin-strap or chain. — 1777
2. •
   A form of beard that follows the jawline but does not cover the rest of the chin.
3. •
   A band of colour below a bird's mouth, resembling the chinstrap of a helmet.

   • A miniature look-alike of the Canada Goose, with a partial white necklace instead of a white chinstrap. — 2003