'fastball' definitions:

Definition of 'fastball'

(from WordNet)
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 'fastball'

From: GCIDE
  • fastball \fast"ball`\ n. (Baseball) a baseball thrown with maximum velocity.
  • Syn: heater, smoke, hummer, bullet. [WordNet 1.5]

Synonyms of 'fastball'

From: Moby Thesaurus