A young man in a dinner jacket.
- The definition of a dinner jacket is a formal jacket or a tuxedo jacket.
An example of a dinner jacket is what a man might wear to a formal affair such as a dinner dance or his wedding.
a tuxedo jacket
(plural dinner jackets)
- (US) A jacket, often white, corresponding to a tuxedo jacket.
- (UK) What the US terms a tuxedo, nearly always in black.