Definition of stiffeners:
(n) :
Anything added to something in order to stiffen it, such as a support beam, or starch for a collar.
(n) :
(construction) One of a series of angle bars, Z-bars, beams, rods, or other shapes, attached in order to provide them the necessary stiffness or rigidity.
(n) :
(slang) An alcoholic drink taken to fortify oneself.