Underwire is a common term used in women's lingerie that refers to a wire inserted into the bra cups to provide shape, support, and lift. However, there are several synonyms that are used to describe this type of wire. In some regions, it is referred to as a "hockey stick," while in others it is known as a "bone" or a "stave." Other common synonyms include "metal cradle," "bra wire," "cup wire," and "bra skeleton." Each of these terms describes the same type of supportive wire that is commonly found in bras and provides structure and lift to women's breasts.