Gusset

Part of speech: noun (n.)

1. A small piece of cloth inserted in a garment, for the purpose of strengthening some part or giving it a tapering enlargement. Seam and gusset and band. Hood.

2. Anything resembling a gusset in a garment; as:

3. An abatement or mark of dishonor in a coat of arms, resembling a gusset.