Webster's Revised Unabridged Dictionary · 1913

gotcha

gotcha (gun"nu) , phrase

[phonetic transcription of colloquial speech.]

Got you; I got you; as, I gotcha!.

Phonetic transcriptions of rapid colloquial speech are sometimes used in place of the grammatically proper spelling in order to provide a flavor of the original spirit of a spoken dialogue. See also the related entries for gonna, gotta, wanna, and wannabe.

gotcha (gun"nu) , noun

[phonetic transcription of colloquial speech, from got you.]

A situation in which a mistake by one person which is pointed out by another person; see gotcha, phr.. [colloquial, phonetic spelling]
2.
A situation in which an error or indiscretion by one person is deliberately caused by another person -- a mild form of entrapment with malicious or humorous intent; as, he was furious to be the victim of a gotcha
Kathleen "Kit" Gingrich (Sept. 23), 77, mother of former House Speaker Newt Gingrich... became famous as the victim of a "gotcha" interview by CBS's Connie Chung; the TV personality coaxed ("whisper it to me, just between you and me") out of Mrs. Gingrich a nasty comment attributed to her son concerning then-First Lady Hillary Rodham Clinton -- and then aired it. — World on the Web [Obituary notice: October 4, 2003]
3.
A situation or attribute which tends to cause one to make an error; as, one of the main gotchas in learning English is the frequency of non-phonetic spellings.