We found 8 dictionaries that define the word be on the ball:

General (7 matching dictionaries)

1. be on the ball: Vocabulary.com
2. be on the ball: Cambridge Advanced Learner's Dictionary
3. be on the ball: Dictionary.com
4. be on the ball: Rhymezone
5. be on the ball: FreeDictionary.org
6. be on the ball: Mnemonic Dictionary
7. be on the ball: TheFreeDictionary.com

Miscellaneous (1 matching dictionary)

8. be on the ball: Idioms

Definitions from WordNet (be on the ball) ▸ verb:  be well-informed Opposite: sluggish, unprepared, unfocused, unproductive, inefficient ▸ Words similar to be on the ball ▸ Usage examples for be on the ball ▸ Idioms related to be on the ball ▸ Wikipedia articles (New!) ▸ Words that often appear near be on the ball ▸ Rhymes of be on the ball ▸ Invented words related to be on the ball