Bat.

• bat [countable]
• 1 a small animal like a mouse with wings that flies around at night ➔ fruit bat
• 2
• a) a long wooden stick with a special shape that is used in some sports and games:
• a baseball bat
• a cricket bat
• b) British English a round flat piece of wood with a handle, used to hit a ball in table tennis [= paddleAmerican English]
• 3

   be at bat

  to be the person who is trying to hit the ball in a game of baseball
• 4

   do something off your own bat

  British English informal to do something without being told to do it:
• She went to see a solicitor off her own bat.
• 5

   do something right off the bat

  American English informal to do something immediately:
• He said yes right off the bat.
• 6

   like a bat out of hell

  informal very fast:
• I drove like a bat out of hell to the hospital.
• 7

   old bat

  spoken an unpleasant old woman

• ➔ as blind as a bat

   at blind1 (1c)

Definition from the Longman Dictionary of Contemporary English
Advanced Learner's Dictionary.