underwire

/ˈʌndərˌwaɪər/
adjective
  1. Describing a bra or similar garment that contains an underwire for support.
    • She bought an underwire bra for a special occasion dress.
    • The store sells both underwire and wireless options.
    • Underwire bikinis are popular for their shaping effect.
noun
  1. A thin, curved piece of metal or plastic sewn into the bottom of a bra cup to provide support and shape.
    • She prefers bras with underwire because they give her better lift.
    • The underwire poked through the fabric and irritated her skin.
    • Many sports bras are designed without underwire for comfort during exercise.