From Longman Dictionary of Contemporary Englishgussetgus‧set /ˈɡʌsɪt/ noun [countable] DCCa piece of material that is stitched into a piece of clothing to make it stronger, wider, or more comfortable in a particular place
Examples from the Corpus
gusset• Cotton gussets were, quite literally, meat and drink to us.• A gore or gusset is, in fact, another name for a scoot.• Four or five horse-shoe buttons were sewn to this gusset as an extra decoration.Origin gusset (1300-1400) French gousset 