The Collaborative International Dictionary of English v.0.48:

Tennis \Ten"nis\, n. [OE. tennes, tenies, tenyse; of uncertain
   origin, perhaps fr. F. tenez hold or take it, fr. tenir to
   hold (see Tenable).]
   A play in which a ball is driven to and fro, or kept in
   motion by striking it with a racket or with the open hand.
   --Shak.
   [1913 Webster]

         His easy bow, his good stories, his style of dancing
         and playing tennis, . . . were familiar to all London.
                                                  --Macaulay.
   [1913 Webster]

   Court tennis, the old game of tennis as played within
      walled courts of peculiar construction; -- distinguished
      from lawn tennis.

   Lawn tennis. See under Lawn, n.

   Tennis court, a place or court for playing the game of
      tennis. --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

tennis court
    n 1: the court on which tennis is played