aha moment

:  a moment of sudden realization, inspiration, insight, recognition, or comprehension The aha moment you experience when you've been trying to remember the name of a song and three hours later it hits you … — Jeffrey Kluger ◆Aha is sometimes followed by an exclamation point and is also often placed in quotation marks. That was the “Aha!” moment … that made the befuddlement worthwhile. — Robin Marantz Henig Her “aha” moment came about two years ago … — Emily Weinstein