We found one dictionary that defines the word ping-pong balls:

General (1 matching dictionary)

1. ping-pong balls: Vocabulary.com

(Note: See ping-pong_ball as well.)

Definitions from WordNet (ping-pong ball) ▸ noun:  light hollow ball used in playing table tennis ▸ Also see ping-pong_ball ▸ Words similar to ping-pong balls ▸ Usage examples for ping-pong balls ▸ Idioms related to ping-pong balls ▸ Wikipedia articles (New!) ▸ Words that often appear near ping-pong balls ▸ Rhymes of ping-pong balls ▸ Invented words related to ping-pong balls