Black tie is a dress code calling for a dinner jacket. Invited black tie.
It means a bow tie, and a long straight tie with a dinner jacket is a different thing entirely. Black tie is less formal than white tie, which almost nobody is ever asked to wear.
1nounblack tieA dress code calling for a dinner jacket.
“The invitation said black tie and half the room ignored it.”
black tie is a dress code.
Practised in Manners & Etiquette