CURVEBALL
Etymology
Noun
curveball (plural curveballs)
(baseball) A forespin pitch thrown by rotating the index and middle fingers down and resulting in motion down "curve"
(by extension) An unexpected turn of events initiated by an opponent or chance.
Synonyms
• (baseball): curve (slang), deuce (slang), yakker (slang)
Coordinate terms
• (baseball): fastball, hardball, slider, cut fastball, two-seam fastball, split-finger fastball, sinker, screwball, softball, knuckleball
Verb
curveball (third-person singular simple present curveballs, present participle curveballing, simple past and past participle curveballed)
(baseball) To throw a curveball.
Source: Wiktionary