The Collaborative International Dictionary of English v.0.48:

Tuxedo \Tux*e"do\, Tuxedo coat \Tux*e"do coat`\, n.
   1. A kind of black jacket for semiformal evening dress made
      without tails, usually of black or dark blue color and
      having satin or grosgrain facing on the lapels; -- so
      named after a fashionable country club at Tuxedo Park, New
      York. [U. S.] --[RHUD]
      [Webster 1913 Suppl. +PJC]

   2. The complete semiformal evening suit, including the tuxedo
      jacket, matching trousers, and black bow tie, and usually
      including a cummerbund; -- the style of shirt worn with
      this suit varies, and the outfit may include a dickey.
      --[RHUD]
      [PJC]