hummer hummer /ˈhʌmɝ/

noun

1. (baseball) a pitch thrown with maximum velocity  ( bullet , heater , hummer , fastball , smoke )
   (baseball) a pitch thrown with maximum velocity
    He swung late on the fastball
   he swung late on the fastball
    He showed batters nothing but smoke
   he showed batters nothing but smoke
   
2. A singer who produces a tune without opening the lips or forming words  ( hummer )
   a singer who produces a tune without opening the lips or forming words