Gus″set (?), n. [F. gousset armpit, fob, gusset, dim. of gousse pod, husk; cf. It. guscio shell, or W. cwysed gore, gusset.] 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: (a) (Armor) A small piece of chain mail at the openings of the joints beneath the arms. (b) (Mach.) A kind of bracket, or angular piece of iron, fastened in the angles of a structure to give strength or stiffness; esp., the part joining the barrel and the fire box of a locomotive boiler.
3. (Her.) An abatement or mark of dishonor in a coat of arms, resembling a gusset.