What is mess jacket?

A mess jacket is a type of formal evening jacket that originated in military mess halls. It is typically made of black wool or velvet and features a short length, tight waist, and wide lapels. Mess jackets are often worn with a bow tie, cummerbund, and dress trousers and are popular at formal events such as weddings and black tie affairs. They are also commonly worn by members of military and fraternal organizations, such as the Masons. The jacket has its roots in military uniform dress but over the years has become a staple of the formal wear section.