gousset

noun

1. A small piece of mail, providing some protection where two plates of armor are joined, usually at the elbows, under the shoulders, and behind the knees.

   “At the joint, or bending of the arm, the vambraces were cut obliquely, the vacancies on the inside, when the arms were streightened, were covered by pieces of mail callet [sic] Goussets, and afterwards by a contrivance of plates resembling hearts.”