'fastball' definitions:

Definition of 'fastball'

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

bowl,
cast,
change of pace,
change-up,
chuck,
chunk,
curve,
downcurve,
fling,
flip,
forward pass,
heave,
hurl,
incurve,
knuckleball,
lateral,
lateral pass,
lob,
outcurve,
pass,
peg,
pitch,
put,
screwball,
serve,
service,
shot-put,
shy,
sinker,
slider,
sling,
spitball,
spitter,
throw,
toss,
upcurve