Source : Webster's Revised Unabridged Dictionary (1913)

Ping-pong \Ping"-pong`\, n. [Imitative.]
   1. An indoor modification of lawn tennis played with small
      bats, or battledores, and a very light, hollow, celluloid
      ball, on a large table divided across the middle by a net.

Ping-pong \Ping"-pong`\, v. i.
   To play ping-pong.

Source : WordNet®

Ping-Pong
     n : a game (trade name Ping-Pong) resembling tennis but played
         on a table with paddles and a light hollow ball [syn: {table
         tennis}]