Gusset
(noun)
A piece of fabric inserted into a garment to strengthen or expand a seam or part of the garment.
Origin:
Early 16th century: probably from french goujure 'triangular piece', based on latin gustus 'taste'. the original sense was 'a triangular piece of material used in reinforcing clothing'; the current sense dates from the late 19th century.
Examples:
- The gusset on the side of my jeans ripped open.
- I had to sew in a gusset to make the dress fit me better.
- The gusset in my backpack helped to keep its shape.
- The gusset on the bottom of the tent added stability in windy conditions.
- The gusset of the shirt was made from a different material to enhance durability.