Underwire (noun)

A wire, typically made of metal or plastic, used in clothing, especially in brassieres, to provide support and shape.

Origin:

Mid 20th century, from under + wire.

Examples:

1. The underwire in the bra provided lift and support.
2. The underwire was uncomfortable and poked her all day.
3. The underwire was removable, allowing her to wear the bra as a strapless option.
4. The underwire design was patented and was a popular feature in many bras.
5. The underwire was replaced with a more flexible material for greater comfort.