'Hummer' definitions:

Definition of 'hummer'

From: WordNet
noun
A singer who produces a tune without opening the lips or forming words
noun
(baseball) a pitch thrown with maximum velocity; "he swung late on the fastball"; "he showed batters nothing but smoke" [syn: fastball, heater, smoke, hummer, bullet]

Definition of 'Hummer'

From: GCIDE
  • Hummer \Hum"mer\, n.
  • 1. One who, or that which, hums; one who applauds by humming. --Ainsworth. [1913 Webster]
  • 2. (Zool.) A humming bird. [1913 Webster]