Wordnet 3.0
NOUN (2)
1. 
 badminton played with two players on each side; 
2. 
 tennis played with two players on each side; 
The Collaborative International Dictionary of English v.0.48:
doubles \dou"bles\ n.
   1. badminton played with two players on each side.
      [WordNet 1.5]
   2. tennis played with two players on each side.
      [WordNet 1.5]
WordNet (r) 3.0 (2006):
doubles
    n 1: badminton played with two players on each side
    2: tennis played with two players on each side
Moby Thesaurus II by Grady Ward, 1.0:
20 Moby Thesaurus words for "doubles":
   bout, contest, decathlon, double-header, event, foursome, game,
   games of chance, go, match, meet, pentathlon, play, play-off, race,
   runoff, singles, sport, threesome, twosome