1. curveball - Noun
2. curveball - Verb
(baseball) A forespin pitch thrown by rotating the index and middle fingers down and resulting in motion down "curve"
Synonyms: (slang) curve, (slang) deuce, (slang) yakker
He bit on a curveball in the dirt.
(by extension, chiefly US) An unexpected turn of events initiated by an opponent or chance; an exception or outlier.
Synonym: twist
Life has thrown him a few curveballs.
curveball (third-person singular simple present curveballs, present participle curveballing, simple past and past participle curveballed)
(baseball) To throw a curveball.
I was planning to be a baseball player until I ran into something called a curveball. And that set me back. Ben Chandler
I'm always very excited by something that's a curveball or from left field. Kevin McKidd
It's a very big mental game, all day leading up to warm-ups. You're not sure if your curveball will break, or will you be able to throw it over the plate? It's all negative thoughts going into the game. Al Leiter
John Wetteland had a very good curveball. He threw it for a strike, too, in any count, any situation. But, he really didn't use it much. He didn't want to throw it. He wanted to throw fastball-slider. Jorge Posada
Hideki Irabu had a very good curveball. Just a straight up and down, swing-and-miss curveball. Jorge Posada
A lot of the times he would use his fastball, he used his curveball, a pitch with fantastic movement. Source: Internet