A tuxedo or ‘tux’ is a formal dinner suit most often worn to a black tie wedding or special event.
A tuxedo jacket is distinguished by its satin lapels.
Tuxedo pants include a similar satin stripe or wide ribbon along the length of the outside seam.
Merriam-Webster Online Dictionarytuxedo (noun)
a men's single-breasted or double-breasted usually black or blackish-blue jacket
a semiformal evening suit for men