Definitions:

1. A sleeveless upper-body garment, usually worn over a dress shirt and necktie and below a coat as part of most men's formal wear. NOUN
   • The tailored waistcoat added a touch of elegance to his outfit.
2. A sleeveless, fitted garment worn over a shirt and beneath a coat or jacket, typically as part of a formal suit. NOUN
   • He wore a navy waistcoat with a matching tie to the wedding.

Synonyms:

• formal vest
• suit vest
• vest