GOTCHA
Etymology 1
Contraction
gotcha
(colloquial) Got you; have you; as in capture or apprehend.
(colloquial) Understand you; comprehend you.
(colloquial) Got you covered, got your back; when you have an advantage or responsibility over someone.
(colloquial) Got you back; as in after causing some form of retaliation or revenge against someone.
(colloquial) Got you by surprise; exclamation indicating a successful trick or prank.
Etymology 2
Direct acquisition of gotcha, the contraction of got you.
Noun
gotcha (plural gotchas)
(colloquial) A potential problem or source of trouble.
(colloquial) An instance of publicly tricking someone or exposing them to ridicule, especially by means of an elaborate deception.
(colloquial) An instance of accomplishing a tricky idea or overcoming a difficult obstacle.
(computing) a feature of a system or a program that works in the way it is documented but is counter-intuitive and almost invites mistake or non-function.
Source: Wiktionary