waistcoat

noun2

1. •
   An ornamental garment worn under a doublet.
2. •
   (UK) A sleeveless, collarless garment worn over a shirt and under a suit jacket.

   • In the Victorian Era, exposing your shirtfront in public was considered improper, as shirts were viewed as undergarments. Waistcoats concealed this and helped [to] tame oversized, billowy shirts. — 2025